The Rambam thinks people are not inherently moral. Even the level of natural law before Mount Sinai had to be revealed in some way.

 When reading the Guide  for the Perplexed of the Rambam straight it is easy to miss this. This is why Reform Jews are right for making a study of the Rambam's Guide. If you don't make it into a serious subject of study, it is easy to miss important points.
Or what often happens is people come up with their own ideas of what Torah ought to say, and then think that that is what is actually says even though their ideas contradict the Rambam. As if they think they understand the Torah better than the Rambam. Now sometimes they depend on Nachmanides, and that is OK.