As I've written about before, in some quarters there is a habit of saying that everything added to Unix needs to be 'Unixy'. One of the many problems with this is that a number of aspects of Unix itself are not 'Unixy'. I don't mean that in a theoretical way, where we debate about whether a particular API or approach is really 'Unixy'. I mean that in a concrete sense, in that Bell Labs, generally regarded as the home of Unix and the people who understand its essential nature best, built various things differently than mainline Unix. In some cases they did this after mainline Unix had established something, which is a clear sign that they felt that other Unix developers had gotten it wrong.

(In the end their vision of the right way to do things was so extreme that they started over from scratch so they didn't have to worry about backwards compatibility. The result of that was Plan 9.)

The easiest place to see this is in the approach that Bell Labs took to networking. Unfortunately I don't believe that manual pages from post-V7 Research Unix are online, but the next best thing is the networking manual pages for Plan 9 (which has essentially the same interface from what I understand). Plan 9 networking is completely different from the BSD sockets API that is now the Unix standard; it is in large part much more high level. You can read about it in the Plan 9 dial(2) manpage, and a version of this interface without the Plan 9 bits has resurfaced in the Go net package's Dial() and Listen() APIs.

You can certainly argue that these APIs are fundamentally not comparable to the BSD sockets API because they're on a different level (the BSD sockets API is a kernel API, while most of the Plan 9 API is implemented in library code). But in a sense this is besides the point, which is that the Plan 9 API is how Bell Labs thought programs should do networking.

(You can also argue that the Plan 9 API is insufficient in practice and that programs need and want more control over networking than it offers. I'm sympathetic to this argument but it does open up a can of worms about when one should discount the Bell Labs view on 'what is Unix' and what can replace it.)