I faced a similar challenge in a product development company full of millenials and designers. That is a fact: they usually complain about the strict process. I found that a good solution is to offer them the benefits of the rules. That is, explaining that the process gives more space to the individuals for solving their own problems through experimentation. I usually explain that the IDM process is not a brainstorming, because we want to quickly put the proposal into practice and test its effectiveness through trial and error.
I hope it helps you