I have no doubt in my mind, if the United States was a country without checks and balances and the protection of the Constitution, we would be living under authoritarian dictatorship right now. The quickness by the administration to attack media, promote propaganda, and now censorship is frightening.
Checks and balances require the separate branches to be willing to apply them. With the apparent lack of any meaningful oversight by the legislature, it does not seem like the checks and balances are working very effectively.
I suppose that's a strong reason why many (including myself) prefer divided governments, so that adversaries can keep each other from going too far.
I don't remember where I read it, but something like this rings true: the founders anticipated authoritarians seeking power, but they did not anticipate legislators allowing it.
Edit: I don't mean to say that Trump becoming a dictator in the US is possible; I think that's extremely unlikely. I simply mean that there is a weakness in the US political system when government is controlled entirely by one party, and that this weakness could possibly be exploited some day.