I agree that Nintendo doesn't have a monopoly on what's quality and "hype" and I think that's a good point to make, but the opposite is also true. It often feels like "third party" is conflated with "hype, exciting, good choice" in the community, while "first party" is conflated with "boring, safe, chosen by committee". There's Nintendo characters that could be great in Smash, Nintendo characters that are probably better off not in Smash, third parties who would be awesome in Smash, and third parties who should stay as far away as possible from Smash. Variety is the spice of life and it seems that (at least from my view) most of the thread seems to agree that both extremes are bad. Very few people want a first party only pass, while equally as few people want a third party only pass. In fact, I mostly see the idea of Nintendo or Third Party exclusivity brought up when one side is trying to straw man the other. A balance seems to be agreed upon as the way to go.
Where I somewhat disagree is your Bandana Waddle Dee vs. Dante example. I think a lot of people tend to think about the most "hype" choice for a Smash game by who can get the most people screaming at their hypothetical trailer, but that's a poor way to operationalize that. Smash, for better or for worse, has gained a reputation as "Gaming's Hall of Fame". For a lot of people who either play Smash very casually (like, played Ultimate for the first month, put it down, and maybe pick it back up once a year when they have friends over) or don't play Smash at all, advocating for a character in Smash is less about getting them in a platform fighter and more about getting them in the hall of fame. They'll watch the trailer, discuss it a little online, forget about it a week later, and maybe will download the character and play for an hour one afternoon.
Contrast this with people who play Smash frequently with friends, online, or at tournaments, pour over every statement Sakurai said to figure out exactly how the game is made and how he adds characters, and spend hours making hypothetical movesets for their favourite characters. Those people who don't just care about Smash as a laundry list of gaming characters, but a love letter converted into a platform fighter. They don't just watch that trailer solely because they want to see a model of the character beat up other characters on screen, they want to see the subtle nuances and details that either reference their origins or will impact the way they play. The characters who get this section of the fanbase excited should, in my view, be the ones really worth discussing when addressing the impact a character has, not the characters designed to appeal primarily to the first section. Characters that appeal primarily to the first camp may get more eyes, but characters that appeal primarily to the second camp tend to get more mileage with each view they get.
A lot of the people in the second camp are, well, Nintendo fans. They grew up with Smash Bros because "I like x from this game and I like y from this other game, and I get to make them fight in this new game". Likewise, that leads to a lot of people who are very much into Smash also being very much into other Nintendo franchises. As such, many Nintendo characters can get a lot of mileage in the core community that may not be seen in mainstream, general discussion of Smash Bros on general gaming forums like Resetera or /v/. Taking this back to the Bandana Waddle Dee vs. Dante example, there's no question that, in a vacuum, Dante would be a more popular choice for a gaming crossover than Bandana Waddle Dee. However, the average Kirby fan is more likely to get something substantial out of Bandana Waddle Dee being Smash than the average DMC fan is to get something substantial out of Dante in Smash just because of the demographics of the fanbase. The average Kirby fan probably grew up on Nintendo consoles and other franchises, so who gets into Smash period probably has a lot more barring on them. The average DMC fan, who may play Smash, but could just as likely be a playstation diehard who grew up on the original PS2 trilogy and never really played Smash in depth. To them, Dante's inclusion is little more than a passing "huh, neat". I'd instead argue that Dante's inclusion in Marvel 3 was more of his big crossover moment, seeing how DMC fans (and Capcom fans in general) tend to overlap with being Vs. fans more than Smash fans.
That's not to say Dante doesn't have legitimate fans who care about Smash or he's less of a worthwhile character than Bandana Waddle Dee or he wouldn't be fun or any of that. It's just the idea that Dante would be popular than Bandana Waddle Dee in becoming a Smash character may not necessarily be true. Context can often matter and what's true in the abstract may not translate perfectly. But that's just one facet of why a character could get into Smash, even if you were to cede that point, you can still construct a convincing case for Dante using other information such as his recent Switch releases and Capcom being eager to give Nintendo stuff for Smash.
What I'm not a huge fan of, admittedly, is the latter part of the post where you claim that people are arguing in favour of Nintendo characters just because they believe they're objectively superior and are scared of a third party boogeyman. Either you misread the previous posts or are deliberately strawmanning, because no one is trying to argue the first point. No one here really thinks Nintendo > non-Nintendo (or, at least, no one who's posted so far). People are instead arguing that certain Nintendo characters have unforeseen merits that have led to many people in the fanbase overlooking them. That's not to say they're better than third parties or anything like that, multiple characters can have merits while also being on equal ground. Likewise, skeptism =/= fear. When people are arguing that certain third parties may not be as likely as it initially seems, they aren't saying "This character is bad and doesn't deserve to get into Smash because...", they're saying "I think people are somewhat overestimating how likely this character is because...". Many people are actually open to the ideas presented, they just don't see it happening for one reason or another. It's like saying "Anyone who argues against first parties are just lying to themselves to make long-shot third parties seem more possible", it's ridiculous and obviously false.
If I can be completely blunt, you're doing exactly what you decried against in this very post, you're ignoring or misrepresenting points from the other side in favour of clinging to the position you came in with. No one's attempting to argue their wants as things that are likely to happen. Find one post where someone says "well, I really want them, so they're going to happen". Likewise, no one has attempted to argue that there's absolutely a 0% chance that Fighter's Pass #2 could be mostly third parties, most other posts against that have merely suggested a possible alternative. It's extremely rare that someone speaks in absolutes in terms of Smash speculation, so it's not every post has to be deliberately outlined "with this may or may not happen but...". Likewise, even if someone wanted to argue that Fighter's Pass #2 was going to be completely different from the first, it's fine as long as they at least outline their logic for doing so. Everyone has provided some measure of arguments, flawed or not, that backs up their argument somewhat. If you disagree with it, great! Make a post rebuffing their reasoning and start a dialogue. Demonstrate where the flaw in their reasoning is. Everyone in the thread benefits from sharing knowledge, ideas, and rationale. What people in the thread don't benefit from are posts that try to strawman and prescribe motives to discredit others when you disagree with what they're saying.