I cannot speak for M. DeVault, but one of the interesting things about the API is that accept() embodies two distinct things. A hypothetical alternative API wo

I cannot speak for M. DeVault, but one of the interesting things about the API is that accept() embodies two distinct things. A hypothetical alternative API would have enabled such things as filtering and rejecting undesirable incoming connections before a handshake completes with application-mode mechanisms instead of with kernel-mode mechanisms. People often point to the function calling conventions of the API, such as the "sockaddr" structures and the "errno" mechanism (that has historically been tricky for non-Unix operating systems and for systems where there are multiple C compilers with multiple C runtime libraries). But there are actual architectural decisions that had fairly reasonable alternative paths. I wouldn't say that it's a "mess" because of these alternatives, but it is definitely not the sole and unequivocal way of approaching things; and there were and are tradeoffs to be had.