Sure, it's easy to learn, but why bother when you can just use React Native? Also there are a ton of senior people with lots of years of experience to hire, where Flutter seniors basically don't exist.

With React being prevalent on the web front, why would anyone do a Flutter web app + mobile app?

Flutter release code compiles to AOT code which speeds up execution. React Native has the Javascript engine which can slow things down. For most of us here on HN, who are using flagship phones none of this really matters, however for other parts of the world that have less capable phones, the ability to run AOT compiled apps is a big deal. Flutter is a huge in Africa, mostly because it runs well on a lot of the popular phones there.

Maybe in theory but JS JIT engines are very fast and Flutter can be janky especially on iOS.

Both will perform well, I've made advanced applications on RN that perform well.

They must exist because I’ve been passed up on senior flutter roles. It can’t be me, right?

Except I have yet to find a Flutter site that isn't bloated. It makes about as much sense to just focus on PWAs now.