Could you give some examples of these network distributed OS's that are going full steam ahead? Also interested in why you think those are less clunky than k8s. :)
Plan9 is the ultimate distributed OS. Running programs on different computers is as easy as mounting a remote /dev/cpu file to your process' namespace. Virtual desktop is as easy as mounting /dev/draw. And so on. Many such complicated things that require ad-hoc solutions on Linux are solved on a fundamental level in Plan9.
I wouldn't say that it's going full steam ahead, since its use in the modern world is fairly limited, but the ideas were there, and they have influenced the development of Linux.
I think the more believable scenario is "hey let's see what we can do with the existing Linux systems and sockets and stuff" and then importing the network into the model because it was the simplest solution.
Then again, whether or not should applications be network-transparent-by-default is a discussion for itself. I believe they should. Every program (that does not drive hardware directly) is just a piece of code that glues various OS APIs together. In the case of Plan9, the APIs are the filesystem, and the filesystem can be modified with 9P protocol. If we can use the same local program to perform an operation on a remote machine without any modification, why the hell shouldn't we.