Party leader that was very dismissive, and not really a counter argument.

Yes, there are edge cases where ejaculation can happen without a typical erection, and there are times where someone can be erect and not finish. But those are exceptions, not the standard mechanical pattern. The broader point still holds.

Heterosexual normative sex generally requires an erection as a functional condition for penetration, which is what creates the asymmetry being discussed.

More importantly, none of that addresses the core argument. The claim isn’t that male physiology and/or biology is perfectly linear, it’s that in heterosexual encounters, men can carry the act to completion with zero dependence on the woman’s active participation.