TCP/IP does not have a concept of Presentation or Session. Everything above it is just “Application”, which is more sensible. There isn’t much criticism to be had of layer 4 down, but when they got to layer 5 and 6, they were telecom people sticking their nose in software architecture. You can write networked applications with those layers if you like. I’ve seen it done, and it’s fine. There are also plenty of other ways to architect it that also work just fine.