Pinging someone with a "hey" or "hello" isn't really the same as putting a call on hold. As the site points out, chat is asynchronous, so the recipient doesn't

Pinging someone with a "hey" or "hello" isn't really the same as putting a call on hold. As the site points out, chat is asynchronous, so the recipient doesn't have to wait around as they would on hold. Plus it's a status check. With a call you have instant audio feedback to know they're on the line. Not so with chat. Granted, you don't always need to establish the recipient's immediate availability. But often chat gets used for questions that need answers almost now but don't warrant the time and emotional investment of a phone call. If you don't do a status check, you risk the recipient not being available to answer your question in time. And if they aren't, you'll waste more time typing your question than you would have with a precautionary hello.