Just saw 2 or 3 place in All Bosses Simple and he uses menu glitch. whats the point of it?

Menu skip actually*

It's so you don't have to view the "report card" cutscene after a level, and also so you don't have to view the soul contract animation after beating a boss for the first time. Takes ~5 seconds of menuing to skip ~20 seconds of game. So about ~15 second time save each time.