I think many companies have a chicken-and-egg problem when it comes to cross-platform development. They already engineers for iOS/Android/Mac/Windows and there's established workflows for creating native apps for each platform, so cross-platform experiments are at an inherent disadvantage.

> You will go through multiple iterations to get your UX right.

For high-level UX flows, this is where cross-platform frameworks could have an advantage, because you can iterate without redoing the work for each platform. It might even make sense to use a web framework for the initial prototype and early user trials, and then reimplement in native for performance/details once it's finalized. As a bonus, if you're willing to maintain the web version you could use it as your browser-accessible version.