about "flexibility" and "fit for purpose" but when the rubber hits the road it's "you have to do it this way"

I haven't experienced the tension with engineering vs product really, but it could be because I have a technical-enough background so I know some of that stuff does need to be prioritized (and some can be put on the back burner). What pisses me off is when someone on my team decides to spend their time on a pet project tech debt thing anyway even though it's a lower priority.