The epitome of this mindset I think is "hostile fork" -- the entire notion is nonsensical. The whole point of being FOSS/OSS is the freedom to fork -- by all damn rights, you should fork as you please, and be pleased to fork!
The actual problem is not forking.. its community fragmentation, and more importantly loss of a "source of truth". Of course, maintaining that source of truth is otherwise known as centralization, with all the problems that brings, but there's nothing inherently wrong with forking.. that's just the natural specialization and evolutionary processes at work.
The solution is to make it easier to find those top-tier libraries, and this is orthogonal to forking; mainly handled by blog posts and "official" library listings/recommendations, and things like This Week in Rust.... namespacing or not doesn't really get you anything there.