Maybe. Realistically it won't matter, because any real world server would either need a lot more memory anyway to actually handle application-specific concerns

Maybe. Realistically it won't matter, because any real world server would either need a lot more memory anyway to actually handle application-specific concerns or support a much lower number of clients. Keep in mind that even with a tiny and receive buffer of 16kB plus maybe some TLS state of > 30kB per connection the baseline memory usage of doing anything useful is already much higher than 4kB - unless the only thing you want to do is building a large-scale TCP ping service.