I completely agree.
I’ve been an iOS developper for 8 years (working on apps with millions of downloads, for a French company).
I’ve been fighting management constantly about this, explaining that it would be cheaper to have iOS and Android experts ratherg than « multiplatform » developers. For instance, on iOS side, frameworks and UI change a lot every years, so you want to be able to update your apps quickly and adopt the new best practices (which is easier if you stick to the standard UI without any other framework).
We had other projects that started with a multiplatform approach, to go back after sometimes on « real » native apps (by real, I mean using only standard SDK, UIKit on iOS for instance). Despite these failures, management keep pushing for technology like React Native, Xamarin etc…
I’ve lost this battle: I think that the idea to have half devs is to appealing to business, and you don’t have chance to explain why this is not as simple as it’s seems to be. Or my points were simply not convincing.