My takeaway from this thread is that some people genuinely believe that players should not be awarded for playing well.
Yeah this is hilarious. This is the reason why in games like Call of Duty MW2 and stuff you get rewarded for death streaks and things like that.
If you have skill, you should find it easy.
My personal belief is that games should be made for the best players, not the average joe, or babbling idiots. But then again I've played a lot of competitive games, so that is probably unsurprising.
I'll c/p one of my earlier posts on this subject... though I'm pretty sure this was discussed on the codex a few billion times previously.
The party becoming too powerful when going off the beaten path is a problem in pretty much every game (not just RPG) because of lazy design: optional content that rewards players for doing it by increasing their power. Devs need to balance for the crit path, so if you're doing every single sidequest, it'll pretty much destroy all challenge you can encounter on the main quest. PoE actually does somewhat OK on this front by shifting most of the difficult content into side quests and side areas (e.g. endless paths) to begin with... though honestly, a lot of the side content is easier than the crit path, so doing it isn't any evidence of "playing well".
In case of shooters and stuff, the answer is easy: high scores (or ~cheevos~). It has no actual gameplay effect, and lets the best players compete on the leaderboards. IMO the 'good' (non-lazy) solution in an RPG would be to design the game from the ground up to grant XP only after achieving certain objectives on the crit path, and optional content only rewarding the player in ways that don't directly affect player/party power: opening up certain options in later quests, getting a better ending for a particular faction, etc.