No way in hell did Master Chief and Dante get any good number of votes in the ballot back in 2015, if they ever did get votes it was probably a very small number that can be neglected. Their popularity only really kicked off in Ultimate. Same thing with Doomguy, these characters weren't as popular as they are now ever since the third party barrier was loosened up a bit. If you claim this is a bad example and these characters had major support back in 2015 then by all means provide proof for your statement.
Again, you're solely talking about the hardcore fanbase. These are massively popular gaming icons. That's literally all that's needed to get a good chunk of votes. Keep in mind a good chunk of votes doesn't even have to be 1% of the votes either. There's thousands of characters out there among the votes, and well over a million votes. You're only seeing the visible stuff, but the visible stuff is not the entire story. It's far more realistic that two major gaming icons got its share of votes because, get this, people don't care if they appeared on a Nintendo console or not. It's actually far more common to see people vote for who they want, regardless of these things. Ridley is a perfect example of someone who was blatantly in a bad position, and this was after it was well known his role pretty made him unlikely to be DLC. Coupled with most people not realizing this wasn't for future games, and they still voted for him regardless of the "odds". This applies to tons of characters, as the casual fanbase does not care about that kind of stuff, and they're still important ballot voters. You're not going to often see these people on areas like Smashboards, the home of the hardcore fanbase.
I also did not say the picks in the ballot were not relevant, I was saying the ballot ITSELF was irrelevant and characters now would have to get on their own merits rather than a popularity poll that relied on a significantly smaller playerbase from five years ago. I never said fanpicks won't get in as DLC, I was saying the ballot won't play a role anymore for these characters to get in. If you believe the ballot will play a big role for future DLC picks then by all means explain to me how the ballot got in Joker, Terry, and Byleth. That's the majority of the DLC packs, I'll give Hero the benefit of the doubt because I can see Japanese Smash fans voting for Dragon Quest back then. But no way in hell did the three I mentioned had the ballot impact their inclusions whatsoever.
It wasn't a small playerbase either. It's still pretty huge for the ballot itself. Terry is very easy to explain. SNK alone is one of the classic gaming companies with tons of compelling characters. Fatal Fury along with King of Fighters is a very popular gaming series. Then you have Latin America, a massive fanbase all thing considered. That's not a "small amount of votes" that you can get from Latin America. You don't need to be a top vote to have a "good chunk of votes" either. I'm not sure where you're getting that idea. Again, we have over a million votes. Even 100 votes is pretty notable to begin with, because that's still a lot of people. Yes, it's not even 1%, of course. But a small droplet does matter. We can tell that by seeing how big Golden Sun's representation came up, and to be frank, it's not the biggest fanbase in the world either. It's no Dragon Quest(which is way bigger since it's most of Japan. There's of course stragglers who don't care about the series). Though that's also barely... 1/4 of the world that wanted Hero? 250,000ish if we go by 1 million being the base total votes?
I never said Byleth or Joker to begin with. That's obviously impossible the ballot influenced them. They didn't exist yet.
I think you're missing a key point; the ballot is intended to be used for future games. It doesn't matter how irrelevant it is as long as there's characters of note to add because of votes. In fact, there's a rumor(as it's not proven and was said by a leaker) that Nintendo wasn't even aware of Isaac's fan demand. Sakurai obviously was, yes. Thanks to the ballot. A lot has changed and they're well aware of what's going on now since old and new players are important.
Like seriously, the ballot is old, had a less voter base than the current Smash fanbase, and didn't even affect the majority of the DLC decisions. I'm seeing more evidence that the ballot won't affect anything in the future if at all.
The idea they used it to begin with already blatantly says they weren't done with it at base(assuming Banjo was from the ballot, which is a fair assumption). And well, no, we can only say it didn't affect half at best. PP, Byleth, and Joker. That's all that's really properly claimable as an educated guess. We don't actually know if it's the literal reason they went for Banjo, it's just a reasonable assumption. But as I noted, Terry and Hero are both very popular characters. Hero especially, and just a "general" one too, not any particular one has a ton of votes from what we can find. Slime too, so DQ in itself appears to have been highly voted. As Sakurai wasn't picking it, Nintendo going for SNK in general didn't seem to really have a business point much to it either. It looked a lot more like a fan demand factor at that point. So it looks far more like it was half the current DLC or most of the Fighter's Pass 1, depending the way you want to look at it. Let's say PP was actually base. That further leads to the ballot influencing most of the DLC too. Likewise, Hero was planned for base, and as I said, we knew of its demand. This is possibly why he tried to get the characters in base too. Massive Japanese demand.
It being old is hardly a dealbreaker either. It still has a crapload of useful suggestions that stand the test of time. There's also no reason to believe they won't continue using it. Especially when there's no new ballot out(and little reason to believe they intend to make one) with their own statement it'll be used for future games. It's pretty clear being "outdated" wasn't a factor even to this day.
Overall, I'm seeing it having a massive influence on Smash Ultimate as a whole, not just base mostly.