Pretty sure that is literally the point of this.

I always felt like this was the whole point of the performance

Yeah, that's pretty much the point of this sort of endurance art.

It's a controversial take that has been the subject of all sorts of debate and even legislation. Some countries don't accept sweeping consent legally for anything, some people/groups think consent must be sought, etc.

She did not explicitly state that she was OK with being touched sexually. Nor did she say she was OK being cut. She said anything goes but I believe monkey paw rules of language apply here. I would argue that the whole point here is that different people take the "permission" to different levels. I personally would never do anything to someone that I would not want done to myself unless and perhaps not even if they gave explicit permission. Here only implicit permission is given and the audience decided how far it went. Your point might have stood if there was some explicitly stated agreement that asexual acts are ok, but frankly I believe it is clear here that it does count as a violation at minimum.

Ya, some things come to mind I'd normally call victim blaming but she basically invited people to fuck with her. If being assaulted in multiple ways didn't cross her mind she was living in a fantasy world. Groups of people are terrible, the larger the group the more terrible they are. One person will push a boundary and then another will take it further, so on and so forth until it's just.... Mob mentality is a real thing and it's not when you see the best of humanity.

Yeah, I'm inclined to agree. She didn't set any limits and told them to do what they wanted to her. Amazing it wasn't worse in the end.

I can't believe how there wasn't a single person in the audience who tried to stop anyone

Yeah, that's not what's written in the Wikipedia article.

Faced with her abdication of will, with its implied collapse of human psychology, a protective group began to define itself in the audience. When a loaded gun was thrust to Marina's head and her own finger was being worked around the trigger, a fight broke out between the audience factions.