Take sockets.c, for example

How many college kids have gotten an 'A' for writing:

// Sockets.c
// send a block of words from a to b
int main(int agc, char *argv[]){}

I see this all over, and i know that when push comes to shove, then it is an hours work to convert that main() to a universal entry, in fact, main() is c already defines a variant of the universal interface.

An hours work? That is equivalent to finding the complete package, setting up the massaging API, and header, and yada yada yada. What we do instead, modify, gcc it and load it, and move on. immediately v=become usable to hundreds of threads and processes who want to swap messages.
Swap them in and out, use multiple version of socket, no problem as long as the enterprise syntax engine tracks names space, again with the motto, there is no way to manage enterprise name space at this level. Use the powerful engines.