Why not just disallow PRs from non-vetted contributors?
Why not just disallow issues without a vetting process?
Many of these things could be explored -- you're right: it's a spam issue. But we have solutions to spam issues ... filters. LLMs have shown that "praying for the best" with permissive repository settings is not sufficient. We can and will improve our filters, no?
That's certainly going to be the eventual outcome at this rate, yes. Close off the FOSS and go underground. Contributing will now involve negotiating the politics and vetting oneself instead of the quality of the contributions. Rejective, but it feels like it hurts the spirit of FOSS. For an industry that can already be considered a bit gatekeep-y
You can definitely argue we hit that point a long time ago, but this will exacerbate it.