I’ve gotten pretty drunk before, but never enough to not remember what happened. Do people forget that much? I assume that they do given the general acceptance of that kind of story beat
Can happen, speaking from experience. Usually you only realize you had a blackout when someone mentions you did something the night before and you have absolutely no recollection of doing it.
Although I never had blackouts of extended periods of time. Maybe 30 min tops. If you drank at a pub, went home with someone, flirted and had sex, by the time you're done with that a lot of the alcohol is probably already out of your system. You're not gonna forget the whole thing unless you're literally drinking the whole time.