Drunk people can't consent, not just drunk women. That's the point of contention.
Edit: it's worth mentioning that there are definitely limits to this statement. If two people at the nightclub have had several drinks and decide to hook up, that's probably okay. They're two consenting adults, even though they're legally drunk. The issue is when one of the people is significantly impaired, to the point where they can't really think clearly and consent or object. Just having a few beers and fucking isn't a crime, and anyone who thinks it is is a prude.