My notifications
are always off. When I do have time to respond, if someone has sent me an actual question, I can just send them an answer. If all they've said is "Hello," now I have to send them a message asking what they want, which they may or may not receive and respond to while I'm still available to actually answer their question.
What's more likely is that they won't receive the message right away, and when they finally do get it and respond, I probably won't be staring at messages anymore, so there will probably be another delay, only to FINALLY reach the point we could have been at initially if the other person had just started with asking the question.
That's the delay on both sides that is needlessly introduced by sending a message with no value.