[w10-1]

It's not intelligence, respect, signaling or status.

It's saving time, the thing we can't bank or stretch or keep. Doing that reflects value priorities that are likely to lead to success and happiness.

We would all be this brief if we weren't constrained otherwise. People who care deeply about their time are this brief even if they shouldn't be. You can even say nothing in ways that influence others in the ways you want (from spiritual teachers and parents to politicians and mafia dons).

(Wealth and power trashing is all too easy these days. Pick a hard target?)

[MichaelDickens]

It's both. Saving time is a form of status signaling. Professionalism usually entails spending longer on something than is optimal for effective communication, which is a way of signaling "my time is less valuable than yours". Writing short messages with grammatical errors is a way of signaling "my time is more valuable than your comprehension".