Most multiplayer games have some way to limit XP gain from encounters outside your difficulty, to avoid exactly this sort of cheesing. The worry is that it allows players to get through the content quicker, with (possibly paid) help from others, which presumably makes it less likely they’ll stick around.
(Though of course an experienced player can still level vastly faster, since most players don’t take combat anywhere near optimally to maximize xp gain.)
That said, Morrowind famously contains an actual intelligence explosion. So you tend to see this sort of stuff more often in singleplayer, I think. (Potion quality triggers off intelligence. Potions can raise intelligence.)
Most multiplayer games have some way to limit XP gain from encounters outside your difficulty, to avoid exactly this sort of cheesing. The worry is that it allows players to get through the content quicker, with (possibly paid) help from others, which presumably makes it less likely they’ll stick around.
(Though of course an experienced player can still level vastly faster, since most players don’t take combat anywhere near optimally to maximize xp gain.)
That said, Morrowind famously contains an actual intelligence explosion. So you tend to see this sort of stuff more often in singleplayer, I think. (Potion quality triggers off intelligence. Potions can raise intelligence.)
And of course the entire genre of speedrunning—see also, (TAS) Wildbow’s Worm in 3:47:14.28(WR).