Is it fair to assume that every individual library/API can somewhat easily create a brand-new-world with every release (because it won't compile until the types are "re-aligned") yet they don't bother to check if the new release works with any other library/API?

I think the problem is partially cultural with a specific ecosystem but also fundamental. It takes a lot of type craft, care and creativity to design future-proof function/method signatures that are "open" to extension without breakage.