...I do wonder though. If two very drunk people have sex, which one is the rapist?
If persons A and B are drunk and A says no to sex but B forces themselves onto A then B is a rapist even though they were drunk.
If both A and B said yes to sex because they were so drunk but regret it later... That gets more difficult and I think it would be fair to say that both are equally to blame for a stupid decision.
The main deal about having sex with someone who is too drunk is that a sober person who is (presumably) able to think clearly makes a conscious choice to take advantage of a defenseless person. If both (or all in case of an orgy) people are completely wasted then it's not that clear (or at least it is not as easy to prove in court) that there is someone who decided to put another person into a defenseless state and take advantage of their vulnerability.