Yes but the OP doesnt seem to be talking about challenge so much as the speed of levelling. So you do a quest and get X chunk of experience, they seem to want less experience, hence turning it off now and then. There is a diff obviously between doing what I have been (which is a bit of a self challenge) and slowing down the rate between those dings up.
I’m personally not against the idea of slowing the level gains down if people want it. I just wonder if this idea you mentioned is put into the Legion Remix, how many will actually use it. People say they will but might find they don’t enjoy the process as much as they thought, especially in a game where timegating gameplay is so disliked.
But I’m not fixated against it, especially if its a choice. Choice is obviously good for the game going forward. 