We already had this conversation. And while yes, the reality is that some people can't take care of themselves, the solution is not the complete bypass of consent. There are ways to create environment where peers can be of help. This is not what institutions are currently, they are more like ... well psychiatric institutions.
No, but I wouldn't just let them be in an abusing family where parents can be dangerous. The simple fact of being able to do things, does not mean, we have to have it. In this case, the solution is collective parentality. This reduces the risk of harm.
Because having a looser grasp at reality doesn't not necessarily means having no way to give consent or not to being aware of the violence and abuse of the psychiatric institution or a process of dehumanization.
Again, we are mad, not stupid, and it goes even for the people who have a more complicated relationship with reality too ("skyzophrenic" people for ex). Like children, we are people and like children, our environment shouldn't get to dispose of us like we are some burden without agency. That mentality is the reason children are abused in silence and the reason mad people face psychiatric abuse... also with silence.
The lack of grasp on reality is neither an excuse with kids neither an excuse with mad people.