I believe it's more complicated than saying slop is required for niche and education content.
That said, we've already decided that truly open systems are not viable. That was settled years ago. Now even 4chan has rules.
Right now we have algorithms that promote terrible content based on automated metrics that don't make the good stuff any easier to find. Especially considering the consolidation of platforms into a few hegemonic sites.
In that sense we already have gatekeeping, it's just a terrible approach to it.
And for the record I mind the slop because of how easily it drowns out and eventually overtakes the good stuff. Even good, educational content feels the need to cater to the algorithm to survive.
We're not at a tipping point yet, but it certainly feels we're headed in that direction.
Algorithmically promoting tastemakers might be a solution. Pushing the good content to the top and burying the slop.