When I get kinky with someone and let them spank me, tie me up, or do something to me where I’ve given up control, I need to trust that they are fully present in the moment and nothing impairs their judgement. Someone who’s had too much to drink or gotten high may not be able to respond to my safeword or judge the tightness of a knot or even realize they’re hitting too hard or in the wrong spot. On the other hand, if I’ve had too much to drink, I may not be able to give my safeword if things get too rough or painful.
Let’s flip the coin. Maybe a Dominant isn’t the only one who’s had too much. Submissives can get drunk too. Well, now we have a different problem. It is possible to be too drunk to legally consent. Someone who is clearly intoxicated, unable to think clearly, speak well, or basically acts drunk (or high) is probably too drunk to give clear and obvious consent to play or sex.
If you play with someone who’s really drunk, and they cry foul the next day - which they may because in their drunken state they could have been confused or believed the scene was part of a dream - you’ll be the one who’s responsible, not them. Consent is such a key element of BDSM and kink, you should never put yourself in a position to wonder whether you really had consent or not - or as a submissive, to wonder if you really consented to what happened.