I don't care about anyone's 'credibility'. He could be the best game designer in the world. That doesn't make his claim that it's impossible for a low tier to win a major any less false.
When has a low tier ever won a major?
You can't expect every low tier to be the next Ice Climbers (which to be fair were already considered mid tier before the wobble was discovered).
I believe Ice Climbers were the biggest jump in competitive viability in a Smash game.
Mang0 brought Puff into the spotlight. It was a gimmick character much like Ice Climbers where the gimmick didn't really get developed fully until later in it's life. Puff was always mid-tier before it jumped though, it always at least had potential.
What is buffing low tiers going to do in a game well supported by patches?
Oh no, something was discovered! Boom nerf and then they are back to character parity.
You are thinking of patches as if they are irreversible. They aren't.
Luma's HP got nerfed, then buffed back to what it was in the following patch.
I think buffs should be the focus of the patches though. Nerfs are a little unnecessary early on in the metagame outside of glaring issues like pre-patch hoo ha.
You try to sound like you are thinking of the game's future but you don't even consider the fact that patches are not final changes. Which is why it is easy to see that you have a very shortsighted viewpoint on patches in general.
People can keep discovering things even as patches release.
Also, early Melee meta and early Brawl meta are not equal to early Smash 4 meta.
Melee released in a time before streaming video was common. You couldn't watch streams to see match ups or what was viable. Your opinion of the competitive game was based on the best player in your area.
The community was not developed and it wasn't for years that the community had any kind of central online presence. It even took a while for people to explore wave-dashing and dash dancing even though they were discovered early on. If a wavedash was discovered in Smash 4 today, everyone would know how to do it tomorrow.
Even back then, the best characters found a way to separate themselves from the rest of the cast very early. Marth and Shiek were high tier from the very start of the game. Isaiah showed off Falcon pretty early on. Fox and Falco were top. As was Peach. There weren't many really high tiers that were discovered later. Ice Climbers and Puff.
People can get a good idea of what makes a character good or bad relatively quickly. Movesets are limited, you can learn framedata on a full moveset in a day to figure out what makes an option good or bad. Characters with more good options tend to do better as they are more efficient with mix-ups because then you don't have to keep doing the same good option as the good option should be covered by your opponent. So a character with only one good option either had to play into option coverage or use a poor option. That is what makes a character low-tier.
I will admit, I don't personally have the most experience in Smash at a competitive level. Though this is probably my 10th competitive game (I've played shooters, fighters, and card games at a competitive level). I know how to play games competitively at a high level. I've done my research, I can make proper reads and cover options but I'm still a scrub because I still have bad habits and my punish game sucks (due to lack of experience). So despite being inexperienced in Smash, I am very experienced in competitive gaming, it's something I love to do.
That being said, between 3DS and Wii U versions I have about 300 hours clocked in these games which isn't bad. Though I don't have the experience of having come from older Smash games.