It sounds like at least some people here think the main problem is with two people who have both chosen to become heavily intoxicated and therefore might think they mean yes but really they’re too incapacitated to make a real choice.
That’s not really the main problem. Sure, that happens all the time, but that’s not when (the vast majority of) women wake up realizing they’ve been raped.
It’s when the man has gone out of his way to find (possibly even causing) a woman to be more incapacitated than he is in order to maintain control over her. He might be slightly drunk, but he’s made sure she’s had 4 doubles, or spiked her drink in some way. That’s a much bigger problem.