It’s a feedback loop. In order to raise your academic profile and potentially get a job, you need a solid CV full of peer reviewed publications. In order to get published in the first place, you often need money and institutional backing.

If you circumvent that cycle by self-publishing (a solidly logical idea btw), then you’ll have an even harder job getting people to take you seriously and will alienate yourself from “mainstream” academia. It’s messed up. Some open access journals have tried to solve this, with some success, but it’s a systemic problem.

20 years ago we relied on printed books and libraries. I've noticed in real time this last decade [nearly] every paper gaining a PDF download button on some website.

its complicated, if yuo try to publish yourself employers might see your research could be biased or fudged results. they want to see a legitimate publication. much like how a certain wealthy billionaire is doing "research" on himself and publishing it, its not legitimate and is considered pseudoscience.