Allowing players to go back and try to get different endings in a game is narratively destructive.

The point of giving a player choices is to help them engage with the story, but if they want to see every ending, they'll just try everything in order which goes counter to that intention.

The concept of good/bad endings is worse, getting a bad ending is a reward to a completionist player, so the ending doesn't actually feel bad which it should.

Some games try to overcome this with various small choices that have small effects later on, which I find nice but it relies on the choices being small and the basis of the ending has to remain fundamentally the same.

An interesting idea I had is to allow the player to choose a route or ending, but warn them plainly in advance that choices are permanently applied to their save file and there is no way to go back and try the other options.