Melee is still very limited in character variety in the higher tiers of competitive play; the dude using Peach seems to be the only one who can afford to go outside the 5 character comfort zone. Nobody's dissing your fav game, but its pro scene has some pretty limited viability right now just due to the way it works compared to other fighting games.
Afford lol peach wrecks fox. Chain grabbing fox is really easy with peach.
Many people don't like using peach that's my guess anyways. Heck I don't want to play peach even if she is really good. Many people prefer other charaters and my guess is that they don't want to play a sissy charater like peach since if I'm honest fox needs to think twice before going into a peach.
Aside from that ice climbers, samus, pikachu some falcon's do pretty well to. and are all players in top 20 range.
Regarding other fighting games usually it is the same way a top 10 or less characters wich are competetive viable while the rest of the cast dies out.
There are always a select group of charaters that people use, It's unavoidable that every character is balanced. In games like street fighter II the cast consisted of only 5 characters to be competetive viable while iconic characters like Ken and RYU were bottom tier and not suitable for competition.