Meleesetheers are so frustrating, complaining about people who enjoy the game "abusing" glitches. L-cancel was a mechanic but it is reasonable to assume the devs didn't know or weren't aware of the gameplay consequences of wavedashing, air interrupts et. al.and guess what, it doesn't matter. It's called emergent gameplay. And I'd wager is probably one of the best cases of emergent gameplay ever in gaming because it doesn't break the game as much as you think it does. Every character can wavedash and l cancel, some use air interrupts like Samus. Hell, Luigi, the character with the best wavedash isn't even top tier, and would be shit if wavedash didn't exist.
Of all the other cases of emergent gameplay that I know of, some even more divisive than Melee, like CvS2 roll canceling, SoulCalibur's 2 step guard and 2G, Tekken's korean backdash and Street Fighter 2 combos (yes, they were unintended) the only ones I would consider on par with Melee on how they both change the game and open up possibilities that enrich gameplay are Tekken's movement and Street Fighter 2 combos. Combos are a staple of the genre and they were discovered by players, same here.
Death of the author niggas, who cares if Sakurai removed these gameplay options from subsequent games; we're playing melee, not smash ultimate nor brawl.