Maybe this has always been Donald Trump's management style, but before he was president we had no reason to be all that aware of it. Maybe in his business empire, when he was unhappy with an underling, he made it known by telling anyone and everyone else who would listen until the humiliated underling got the message and got in line.
I don't know. Trump figures that what worked for him in business will work for him as president, and the insistence of the political class to the contrary did not prove correct during the election campaign.