We have people in my company that do that in slack. They usually do it because they are canvassing for someone to respond (they ping different people and wait a few minutes between each - under some pecking order).
If the first person responds the real question is typed out to get the help they need.
If it's someone less useful in the domain the next question is usually - hey do you know anything about the email system. Instead of the real question.
I think it's just a conversation style that translates from real-life problem solving.
I've certainly done something similar, but with some very minor tweaks, this can be done in a respectful way.
I'll usually write up my question and post it in a public channel. Then, depending on the situation, I might `@` one (or more) of the people who's insight I'm primarily seeking, but because it's public, others can take a look.
If my primary person doesn't reach out, I'll copy the URL of the message as a DM to the next best person, and ask if they've got advice/thoughts.
Either I or the person who looked into it will add a comment to the thread like "resolved" or "ok, {so-and-so} helped me figure out the problem, which was..."
If the first person responds the real question is typed out to get the help they need.
If it's someone less useful in the domain the next question is usually - hey do you know anything about the email system. Instead of the real question.
I think it's just a conversation style that translates from real-life problem solving.