>> I've got a theory: The blowjob is the ultimate act of sexual dominance and submission. <<
A singular, myopic perspective that seems to ignore male sexual development as well as the differences in what each gender might experience as sexual desirability or 'acceptance'.
At least consider this: As a young man hits puberty, his only intimate experiences with women have generally been asexual. His most intimate female relationship has been with his Mother (generally) and suddenly he is presented with desires which are fundamentally foreign to anything that might have to do with his Mother. At this point, many young men are introduced to a duality regarding female relationships. This is standard sexual development stuff, and all part of whatever genetic 'plan' we homo sapiens still have the programming for.
Regardless, there is now (puberty) an element of shame. Something that cannot, will not be part of the relationship with (again, speaking generally) the only woman he 'loves' up to this point in his life, his Mother.
Specifically, what becomes suddenly private, hidden, taboo is the erection and ejaculation. And I cannot think of a more powerful sign of acceptance (love?) of a man's erection and ejaculation than to for a woman to take them into her mouth, without the rejection and condemnation that any young man would fear from his Mother or his Teacher or his Aunt. In a sense, to say: "I know this about you (this thing hidden/taboo previously), I accept it, I love it."
And I've got a theory: That the males desire for being sexually accepted in this way allows the woman to be in absolute control, absolutely dominate, and he has no choice but to be submissive, to allow her the control in the hopes of finding this acceptance of his sexuality. "Blondie" gets this, she knows this is something that in the sexual dynamic only she has the power to provide.