I think this is an incredibly good example of missing the forest for the trees. The PMs aren't like this because they're glory seeking idiots. They're like this

I think this is an incredibly good example of missing the forest for the trees. The PMs aren't like this because they're glory seeking idiots. They're like this because as far as most of them are concerned, it's their job to constantly tweak the product to achieve business goals (which are almost always "growth"). You can't just fix this by saying "ok let's promote PMs who are obstinate about not changing things" -- this will not align their behaviour with existing customers any better, bad things do still need to change. You'd need to adjust the business goals to be aligned with stability, and that's not something you can fix in a performance review. That's not even something you can fix at a company level. It's just consumption-driven capitalism in action.