> please don't say just hello in chat

In a great many chat (as in one-to-many group chat as in, say, IRC -- where the 'C' stands for "chat" btw) it's perfectly okay when people join and start with just "hello".

I think TFA meant to write: "please don't say just hello in PMs to coworkers".

Not all chats revolves around leveraging synergies to maximize shareholders value while at work.