Matchup charts are too hard in this game. Idk hardly anything about other games, but from my limited experience, it SEEMS like other fighters have fairly strict matchups. Characters often struggle with the range or speed of a certain move, and there's really no way around it. It sounds like the matchup can improve or become more difficult only through relatively minor optimizations.
Melee is so free form that this doesn't seem to be the case at all. Matchups, even by the status quo's opinion over the years, have varied a lot. There's always so much innovation from the top players that a matchup that looked terrible at one tournament can seem amazing at another. A good example is PP's improvements to the Falco vs. Puff game. Most people, myself and even most Puff mains included, were under the impression that Falco got beat pretty heavily. These days, after watching PP compete so well with Hbox (even having a dominating streak over him for a while), it's hard to say the matchup is much worse than 60-40. The problem with calling all the matchups 60-40 is that it changes any time any top player brings innovations to the matchup. Having a matchup chart updated every 6 months based on which top players happen to be playing which characters is dumb, especially since even the different tiers have plenty of matchups that are 60-40 or closer.
I'd be hard pressed to consider any A tier vs. B tier matchup as worse than 60-40. Sheik's B tier matchups and stuff like Falcon vs. Samus definitely seems bad, but I have a hard time believing that if you put a relatively equally matched Sheik or Falcon vs. a B tier main that they'd actually win more than 60 out of 100 matches. Decision making and general good-player stuff simply matters SO much more in Melee that tiers are rarely the deciding factor. Now once you start talking about C and D tier, I think the gap not only gets worse relative to A, but even C vs. D tier seems generally worse because characters' limitations get compounded on every single interaction. But then, who really cares about C and D tiers when probably less than 5% of the community mains those characters? Out of all of them, I think I've only played 2 Link mains, 1 DK, and 1 Yoshi in tournament my entire life.
tl;dr - Melee is too complicated for a "pools tier list" like Varist suggested to ever be useful. Even if you could get that kind of tier list to somehow make sense, do we really want to be encouraging players to pick characters based on what characters are most popular in pools at the current time? Would anyone listen to that kind of list anyway? I feel bad for anyone who wants to main Falcon but plays someone else because a bunch of people told them POOLS will be a little harder starting out with all the Sheiks and spacies...