Profit motivated exclusivity under private control resulted in the enshittification vortex of adtech doom we're currently all drowning in. If you want prestige - top ten status in Google search results - you need to play the game they invented. Same goes for all of academia.
People stopped optimizing for good websites and utility and craft and started optimizing for keywords and technicalities and glitches in the matrix that bumped their ranking.
People stopped optimizing for beneficial novel research and started optimizing for topical grants, politically useful subjects, p hacking, and outright making shit up as long as it was valuable to the customers (grant agencies and institutions seeking particular outcomes, etc.)
Google is trash, and scientific publication is a flaming dumpster fire of reproducibility failure, fraud, politically motivated weasel wording nonsense, and profit motivated selective studies on medical topics that benefit pharma and chemical companies and the like.
Scientific publishing is free speech. As such, it shouldn't be under the thumb of institutions or platforms that gatekeep for profit or status or political utility or any of a dozen different incentives that will fatally bias and corrupt the resulting publications.
It's incredibly cheap and easy to host for free. It benefits everyone the most and harms the public the least to do it like that, and if a prestigious platform tries to push narrative bending propaganda, it can be directly and easily contradicted using the same open and public mechanisms. And if it happens in the other direction, with solid, but politically or commercially inconvenient research saying something that isn't appreciated by those with wealth or power, that research can be openly reproduced and replicated, all out in the open.