Entryhazard
Banned
I think the difference here is that Metroid doesn't stop you from using advanced techniques to get to places that most people would need a new power up to get to. For example, the big alien face cave corridor that is normally inaccessible without the Hi-Jump Boots, can be accessed early with deft use of power bomb jumps or (I think) wall jumping.
Wall jumping makes it so easy to break the game's sequence, and the game doesn't tell you off for trying.
Those are minor cases compared to walls made of missle blocks or doors that can be opened by specific weapons, which are the vast majority of the game.