What you're saying is that you personally don't need to write network code that performs socket(), bind(), listen(), accept(), send(), recv(), etc. But the prog

What you're saying is that you personally don't need to write network code that performs socket(), bind(), listen(), accept(), send(), recv(), etc. But the programming language and library you're using is using those calls, to talk to the kernel, which is doing a lot of the work, so your language/library doesn't have to. And it does that using a standard API. This enables less context switching, faster processing, more uniform behavior, and more portable code. It also means your language/library does not need to implement a TCP parser, which can be quite complicated, and it means the kernel can maintain the more complex network settings that affect your TCP connections, benefit from a shared buffer/cache, network filters, routing, etc. Off-loading protocols into the kernel (or even better, the network card) is a boon to the whole OS and to your individual application.