The President has an entire communications staff within the WH to do this (WACA). He's got the Weekly Presidential Address on Saturdays...he could give Oval Office briefings to the American people the same way that every President until Obama did to reach out and talk to the American people.
He can call a press conference at the WH on any day of the week to discuss issues he thinks are important and that the American people need to know about.
There is no reason why the man who is supposedly the most powerful man on the planet feels he has no outlet for his message but blatant propaganda emanating from Trump Towers posted to FB.
A couple of points. Why are we discussing Obama in this context? Obama had the press on his side. Without that singular advantage, he would never have won a second term.
Trump is faced with the opposite situation. The press is not only against him, they are relentlessly, fanatically against him. He has to figure out a way to counteract that.
Also, we are in a different era now. Facebook has become a powerful political tool. My Facebook page still has a few 'words of wisdom,' doggie spotting and recipes, but it now has more political stuff than anything else.
It's not your parents' Fireside Chats anymore and Trump has moved with the times.