>>283107580 (OP)
IMO the more general trope is "shy nice protag, dominant aggressive love interest". In media aimed at women, the female protagonist is reluctant and the boy is aggressive.
Maybe it's just general human nature to want the other person to take risks, the first steps, and just the lead in general.
From a pure smut perspective, the reader is usually already into the love interest, usually ahead of the protagonist, so they won't mind if the love interest pushes boundaries. Like yeah, I already want to bang them, I won't mind a shut-up-kiss out of the blue.
If it's more pronounced with m/F pairings, maybe it's a response to the recent decades of men being told to dial down various dominant behaviors because it produced way more creeps than chads. Can't accidentally be a creep if you avoid women!
But then if the author still wants to have a couple, the woman necessarily has to take the lead or they'll never get together.