In what way is that better than "Hello. How do I do x?" If they never reply, that's of no practical difference from just sending "Hello" and not getting a reply.
In TCP, it's useful because it happens in a different layer of abstraction. Even then, QUIC was developed (partly) because it was realised there's no point waiting for the full SYN / SYN ACK / ACK before starting some of the higher-level exchange (although the early data transfer in QUIC is used for TLS initiation rather than application-level data).
It's better because X might take a while to write correctly, and you might want some assurance that you have the other person's full attention first before you even send that message. It's a commitment mechanism of sorts.
This doesn’t make sense to me. What does it matter if you have their attention first? It’s asynchronous communication. I find it so damn rude to demand my attention first before you begin typing out a long message. Like do you want me to watch the chat bubble animation while you type or something?
Yes, I do. Sometimes people want (more) synchronous communication despite the asynchronous medium. Among other things that helps guarantee a speedy response. A lot of people use asynchronicity as a way to simply avoid answering in a timely fashion, so framing it like this can make sense if you can't afford that.
In addition, seeing the chat bubbles appear moments after you finish your round is a good sign the other person isn't multitasking and letting their own attention get fractured.
I never found it rude to begin with, just not using the medium to its strengths. But this has me realizing maybe it's a deliberate way to eschew those strengths, for some purpose or another.
In TCP, it's useful because it happens in a different layer of abstraction. Even then, QUIC was developed (partly) because it was realised there's no point waiting for the full SYN / SYN ACK / ACK before starting some of the higher-level exchange (although the early data transfer in QUIC is used for TLS initiation rather than application-level data).