Assuming it works the same way on Hubitat, this bit from the classic ST docs should answer this question:
I never use it since as far as I can tell, there isn't anything you can do with it that you can't already do via either the "typical" method for sending a Z-Wave commands--either the return value of a Hubitat command or "manually" with
sendHubAction(), as you've seen in other threads. I guess maybe it saves a bit of typing compared to creating a
HubAction manually if you're doing the latter? (And really, you still have to do something with it either way--calling it doesn't send anything on its own.) I'd love to hear what people actually like to use this for. It's rare in Hubitat drivers from what I've seen, but I suppose I haven't seen everything.