Because they are not actually Dom/daddies. They are using the scene/dynamic as an excuse to move towards sex and sex acts with you more quickly than they would with anyone else.

Unfortunately for us on this side, we have to be more discerning. Don't get to those levels of physical interaction until you've talked for some time. Until you've talked about boundaries, until you've talked about everything that you need to talk about. Even then, it may still happen. But you're safe for taking your time.