> It is much more difficult to have no mid-layer at all when designing communication protocols than when designing filesystems or other kernel subsystems. Simply because you are not alone. Upgrading your kernel is easy. Having everyone upgrading its kernel is obviously much harder.
I think you're confusing implementation and specification. Nobody, not even the original article, argued that there shouldn't be a "specification midlayer". However, the original article argued that the implementation should not make the "midlayer mistake", which I contested. So far your rebuttal has been on a "specification midlayer" basis. TBH, I haven't even figured out whether you were trying a rebuttal or not, nor what the TCP/IP specification has to do with the original thesis.
Also, you can ignore the fact that I mentioned TCP, and my point still stands with just plain IPv4, it's implemented as a midlayer.
In any case, it would be near impossible to implement networking as a library approach since afaict that would mean you'd have sockets tied to NICs and would have to provide migration for that, or something like that.