This is true. But now what if we looked at it from the opposite angle... Let's say there is a couple (a kinky couple), both the partners are mostly dominant in their lives and yet one particularly wishes for the other to submit. And let's say that other one DOES submit...sometimes...but with no great zeal, and in fact, most of the time, the dominant has to keep reminding the partner that he/she should be a bit more submissive. I think this would become frustrating for both partners, quite quickly.
I agree that, "what you want and what you can get is not the same thing." And that not everyone WANTS to "take over"....but when you've been trying to make the best of it for years and years and it's to the point where you'd rather just skip sex altogether than pretend to enjoy what your partner is doing instead of hurt their feelings, it starts getting ugly.
My situation seems to be a common one here on the library. My husband will do what I ask...he'll tie me down, spank me a bit, might even tussle with me a little, but I KNOW (because he's expressly told me) that none of these are things he enjoys. He gets no fulfillment from it, and in fact, it stresses him out to think that I DO enjoy them---and that that enjoyment probably reaches further than he'd care to examine. So, to save his feelings, I hide that part of myself away.
I tried to make the best of it by explaining what I want. I topped from the bottom. But my "better...at least for a while" is coming to an end and that scares me.