I think this was the one single issue that pushed me to Dom. I as a sub could not find a Dom that I believed had enough control. It's boring. It's frustrating. Goals falling at the way side for the rogue misc session. Doms forgetting there was a mutual agreement. That I too was to gain something from the arrangement.
As a Dom is it hard to keep this all straight? To ignore that throbbing between my legs when a sub is doing their job of being a good slut? yes it's tough. It's hard as hell. It can be torture sometimes.... but it's worth it.
I think I developed the patience and the backbone for this by being a sub.
Do I think the OP's friend is right? nope. I do however understand were his misinformation is developing from.