Calling someone a

slur

cocks*cker

is widely accepted as a homophobic slur, and imo is rather obviously the root of the idea that a person sucking cock is "allowing themself to be used by a dominant figure" as you so neatly put it. The whole idea that the person getting their cock sucked is dominating the person sucking their cock is homophobic. It treats the person sucking cock as lesser. It's how you got the societal taboo of giving a woman oral sex, which admittedly is almost unheard of nowadays, but it used to be that going down on a woman was seeing as feminizing (since you're getting dominated by a woman) and therefore gay.

Asskissing has a completely different origin going back to a poem by Götz von Berlichingen. It comes from a completely different context even though they both are used as largely replaceable idioms.

I should come up with a copy-pasteable answer at some point.