The purpose of speaking alone with someone, clearing the room if you must, is confidentiality. You know that, I know that. Its simple logic. But, if you can not, when you can not trust the other to keep it confidential, one on one (alone) protects your self ……and keeps it “My word against yours”. When the two of us both have some honesty or trust issues, well, it will remain “my word against yours”. How many times has Donald Trump cleared the room in business meetings to speak to a customer….partner, politician? He knows what he is doing! When the information of that “private” meeting gets leaked out, bingo, you know who the leaker is and can only be. How many staff members in the White House has the Donald had one on ones with. Most people would be smart enough to know they can not share information with others that was held in confidence in such a uno a uno meeting. Unless of course you believe that same info has been shared in others private one on ones.
How many one on ones has Hillary Clinton had with all her confidants? After all, the Vince Foster murder order (call it a Hit) came from somewhere. Hillary’s famous constant response “I didn’t do it, somebody else did”.