I play as a guest on my mobile unrated games. I like lichess app for quick pairings.
I play unrated, that is "Casual" rounds. Why not accept a takeback in an unrated round? It's called 'casual' for a reason. If you choose to take it seriously anyway, or if you are in a hurry or dislike the particular round or whatever, fine so be it.
The douchey behavior that I find annoying is when my opponent will accept a takeback but only to one halfturn past the point where I made a blunder. For example, I move my knight to a square that allows one of my minors (that knight or a bishop or a couple pawns) to get captured for free or lose an exchange in 4-5 turns. I don't realize this blunder until three turns later and request a takeback; accepted. Request another takeback: accepted. One more to go; denied. Douche. If he is feeling extra douchey he will then add a bunch of 15sec increments to my clock.
And by the way I don't ask for takebacks all the time or even every round. But they are a nice option in casual rounds, which is one factor that I opt for lichess over other pvp chess apps.