I would never post something like this. I'm just as peeved by "hello" type chat messages as everyone else here, just as I am when someone walks into my office and starts talking to me while I'm doing deep work. But I never want to make a colleague feel bad by doing so. The long term benefits of maintaining a warm and friendly work environment far outweigh the occasional annoyance. Also, most people are smart enough to pick up on subtle involuntary social cues. There aren't many repeat offenders.