I agree, an common, likely OS provided API to resolve names is in the theory the best way to go. Not least because it allows OS vendors to replace the implement

I agree, an common, likely OS provided API to resolve names is in the theory the best way to go. Not least because it allows OS vendors to replace the implementation with more modern and secure variants over time by pushing sane standards. Sadly they didn't do their job and most DNS is still un-encrypted. Eventually others comes along and do it by themselves. Obviously not on the OS level, since they don't have control over that. Yes, "multiple duplicated implementations" is the natural consequence of badly maintained software. But eventually I'd hope OS maintainers get their act together and implementations will start to converge again.