Marking a ball on the green Rule 15.3

Yes you could. But tbh I don’t think pace of play is really the issue…not really. Rather I suspect it’s just that some players don’t like being asked to do something they can’t themselves be bothered to do of their own volition, or that wouldn’t bother them if they were the player to putt.

I also suspect that verbal rejections of such very occasional requests would be very rare, if they happened at all. I just can’t imagine it happening at my place…as hard as I might try.

The above is not to say that those who take an eternity over every shot might not get a polite request from me if we are losing our place. But that is not the same as an occasional request to mark a ball. I might make such a request maybe once or twice a round when in a four ball - and prob not bother at all in casual non-comp golf. Maybe OP experience is of a player doing this all the time on every hole to every other player - when yes - I can imagine that becoming a bit frustrating.

Same number of times asking a player to move (and in any random four ball oddly enough it’s usually the same player ?), though this is less common as most players know where not to stand when another is putting - and it’s usually them simply not paying attention that another is about to play that causes it.