The problem is that the vast majority of established researchers do not care that the system is broken. Why work against the system once you're at the top? Most of them haven't ever thought about it, and the ones who know usually don't do much, because, hey, that's the way it was always done, they are used to the current journals and conferences being prestigious, and they don't want to bother with the unglamorous work of setting up HotCRP or coordinating reviews. Plus they usually want to push their career further and they know perfectly well that fighting against established venues isn't the right way to do that.
As a young tenured academic I have been systematically refusing to do reviews for non-open-access journals. (I'm certainly not senior enough to create a new journal and be taken seriously.) I hoped that this might give some ideas to my peers but it's seen at best as a weird quirk, at worst as a selfish move (because "the community" needs my help to review papers). Usually the answer is some variation of "yeah the system is not perfect".
The only argument I have seen which motivates researchers to care about open access is when it's mandated by funding agencies (e.g., in Europe, the ERC). Researchers really want to get these grants, so when these agencies talk about open access, they listen very carefully. It both makes me somewhat optimistic and quite cynical that the only way to move towards open-access seems to be via funding agencies (as opposed to researchers caring about the problem). Plus, for many agencies, "open access" here means "gold open access", i.e., continuing to work with the usual publishers, who make the articles available online, but move the "costs" (and huge margin) to the authors, with "article processing charges" of $1000-$2000.