Probably because people believe Marth has the niche of tipper-reward spacing without getting other gravy features that put him clearly above other sword users. Just look at what happened to
. Melee Marth just kinda did everything he did but better.
Now
has the swift frame data, auto-cancels and grab game over
to distinguish him, in exchange for his spacing
game not being as rewarding. Instead of grabbing to beat shields, Marth has uncharged Shield Breakers, plus his grab is pretty ordinary for a non-tether. Unless you consider this to be normal: