In my experience, designers work in Figma. Then they play with and give feedback on what the mobile engineers actually built, same as the rest of us. Their critiques become backlog items and it is ultimately up to the PM which of them to prioritize and whether they are launch blockers. They may very well be fanatical about feel, but at the end of the day there is a long line of people who want mobile engineers to change things and they will not always be able to skip to the front. With visuals, on the other hand, they provide the engineers with detailed layouts and assets, so their intentions are almost always carried out precisely.

I agree with this. I think design has a serious principle-agent problem.

A beautiful design will live forever on your personal portfolio, but no one can directly experience usability there. So designers are fighting competing incentives to do what’s right for this product, and what’s right for their professional image. I think this is partly the cause for trend toward stylish-but-less-useable.