Sure. But we can't also actually stop being ourselves to do it. We don't replace ourselves with the other person. We can't actually stop knowing what we know. At second best, we can't pretend we don't know something, which doesn't automatically result in the same choices as if we didn't actually know it. Who we are and what we know always influences our decisions, one way or another, even when we're pretending to be someone else.
On not using XP, totally agree if some other method is used to gain character power, that will instead have some level of influence on player decision making for their PCs.