Facebook was much smaller during Obama's election wins. It also hadn't even moved off the chronological feed at the time he was first elected. Returning back to that type of feed with no boosting content for virality or engagement would do a lot to "fix Facebook".

Also it is worth noting that Obama's campaign was largely based off positive emotions like hope and change while Trumps was largely based off negative emotions like outrage and divisiveness. People are angry that Facebook is manipulating us into negative emotions. People would be less upset if Facebook was manipulating us into positive emotions. So yes, Trump did shine a light on the problems with Facebook but that isn't because of a left/right bias like you are stating.