I wouldn't even argue Hero is top tier. Yeah, he can get some pretty cheesy kills on you, but luck is such a huge part of Hero's moveset, there's no way you can get consistent results with him, especially in a competitive match.
While I don't agree with banning Hero until we get enough quantitative results, I feel like people overestimate how luck is a detriment to Hero. When you pull up the screen, most times you'll get something you need, and if not, you can just keep flipping through until you find one in 2-3 checks. Hocus Pocus unreliable? Then don't use it. MP is supposed to be another balancing tool that is too easy to cheese. Out of MP? Just Smash attack a couple times and you're back to enough MP, within seconds, to use spells. And hey, if you're lucky, by doing Smash attacks to fill MP you may also get a crit and kill them instantly. Too many moves are instant kills, and the bad moves can just be ignored. All
in theory.
In practice, so far, I've yet to see a pro player consistently play Hero in an actual match. So it still is possible that
in practice the character is balanced well to where it's not as broken as it seems. But I have a feeling that's what it's like now, but that could change. While I'm not on the ban train because it's too soon, I am also not a fan of the hypocrisy of not including items (because of luck) but including Hero (where moves are based on items--like Death's scythe, healing food, fake Smash ball)--unlike in a match with items, non-Hero characters can't take advantage of them. But, that's why I don't watch competitive Smash, for the most part, the decisions are weird, and make for a boring watch for someone like me (not to mention banning almost every stage so we see the same ******* Pokemon or EarthBound stages over and over again). Which is why I mostly stay out of this debate--not into competitive play, so I don't get a vote. But, those are some of the reasons why I don't generally watch in the first place.