Absolutely. Even ignoring issues of consent and legality, physical power is the weakest and least effective of all kinds of power. Really, how many things can you actually be physically forced to do? All physical force can do is do things to you, it can't make you do anything. Secondly, it is extremely limited in range and speed. It can only extend as far is the wielder and only move as fast as him/her/it. Other forms of power can be exercised solely through communication, thus vastly extending the reach, speed, and degree of control (as you can actually get someone to do something). The strongest forms leave an imprint on the person, so the effect is not delayed nor weakened by distance and only slowly by time. The appeal of physical force is that it is the most direct kind, not that it is the strongest.
Theoretical ability and actual willingness are two different things. If a person doesn't have the will/desire/knowledge to do something, does the fact that they could do it really matter?If the sub is only choosing to submit, but can say no just like that...the Dom has no physical strength to overpower him/her...
Who is truly the dominant force here? If there is an underlying sense (real or not) that the submissive partner is only indulging the dominant, but can turn the table at his/hers convenience?
Applying physical strength can be a lot of fun because, as noted, it is the most direct form of power. However, as an actual tool for dominance, almost never is it used to keep control. If it comes to that, control is already lost.