A big issue is funding bodies/grant reviewers are mostly old guard who are happy with the status quo. Recently, a big journal was changing in a way that upset a large swath of such people. Unfortunately i can't remember what journal. But it was obvious they benefited substantially as they're more established.
https://www.the-scientist.com/news-opinion/q-a-why-elife-is-...
I am not knowledgeable, but it looks like just game theory.
Ideally, I would wish you to publish in open access while I reap the immediate career benefits of publishing in a prestige journal.
There are several reasons why this has not happened.
1. The most important, researchers are not publishers and are already completely overloaded with other work (most academics typically work 60h+ a week). They neither have the time not expertise to get this started and make no mistake there would be a significant effort required to get this started.
2. There is a certain percentage of researchers who are quite happy with the status quo. These are typically the very successful researchers which don't lack funding so don't see a problem with this (obviously there are exceptions) . Unfortunately they are often also the ones who have a disproportionate influence so if they are not on board the effort is much harder.
3. The vast majority of researchers highly depends on publications in high impact journals for their grants, careers, jobs... (for younger researchers a publication in e.g. Nature can really set off your career). For a new journal to get a high impact takes at least several years, so this is a bit of a chicken and egg problem. Before the journal has the high impact most can't afford to send their best work there, but without that work you don't get the impact.
(This is a not an obscure technique — it's the bit of game-theory that Groupon is based on.)
(We see particular fields switching over to focusing on paper distribution through preprint archives rather than journals; but just using preprints for distribution doesn't solve the problem that journals solve — which is having a sports-like "hierarchy of prestigious competitions" where a paper can either "make it" to being published in the journal that's that field's equivalent to the Olympics, or it can "get stuck" publishing in some "bush league" journal; where this informs, as a first-gloss heuristic, how much attention you should pay to trying to understand the point the paper is making.)