You can easily build a JSON based RPC protocol in a few minutes using WebSockets and be done. With raw TCP you're going to be spending a week doing something millions of other developers have done again and again in your own custom bespoke way that nobody else will understand.

Your second point is very dismissive. You're inserting random application requirements that the vast majority of application developers don't care about and then you claim that only in this situation do WebSockets make sense when in reality the vast majority of developers only use WebSockets and your suggestion involves the second unwanted protocol (e.g. the horror that is protobuffers and gRPC).

> WebSocket is fairly inefficient protocol

In what way?

> This is adding complexity without additional benefit

I'm not sure that's a given. For example, WebSockets actually implement a message protocol. You have gauarantees that you sent or received the whole message. That may not be the case for TCP/IP, which is a byte streaming protocol.