Because the query is an interruption. Frustratingly, about 30% of the time (or more!) the person who sent me the hi doesn’t send their actual question even if I respond almost instantly after it’s sent, so I’ve stopped responding to a bare hi.

Moreover, now that I’m interrupted I can’t really go back to what I’m doing because I know that (presumably) a question is coming very soon, so the interruption clock has already started and I have to sit and wait while they painfully slowly type the actual question.

And then there’s the frequent case where I get a bare hi, but cannot get back to it until a few hours later, and then that person is offline — but I don’t know what they needed, so I cannot ask them and cannot send a response. If they’d have just included their question then I could just answer it and we’d all be better off.

I’ve just gotten to where I just refuse to answer a bare hi… if that’s all you’re willing to type, then I guess you didn’t need anything.