Yeah, I agree with you here. I think the thing most related to that that I see people thinking is that send(2) & recv(2) calls translate 1:1 with packets send/

Yeah, I agree with you here. I think the thing most related to that that I see people thinking is that send(2) & recv(2) calls translate 1:1 with packets send/recv. I.e., that they don't understand that the interface TCP exposes to applications is a byte stream. Which then results in things like thinking recv(2) will receive a complete "message" for some definition of message in the application protocol (i.e., the mistake belief that fragmentation won't happen).