Also, if you could just recompile your app for a new platform and release (more or less), it would remove the biggest barrier to entry for possible new platforms: Adoption.
Now Flutter is making its own widgets that look and handle like the corresponding native widgets. So they need to implement accessibility all over again in the same way that is already present on the platforms. Google is thus redoing all the work they already did in Android.
A lesson from modern software development is that software is developed incrementally and because accessibility is never high on those priority lists, it will lack in quality at first and take multiple iterations to get up to the same level as the native accessibility of the OS, if it even gets there in the first place.
Then again, this is more of an outlier (today) with the GPU present almost on any mobile device, but still something to know about (e.g. flutter won't be of good use there).
> In other words, in today’s market, a branded, custom UI is king.
Does a custom UI per app not make it more difficult for people to learn each new app? Didn't the platform developers write their human interface guidelines for a reason? Or was that level of consistency only necessary in the early days of Mac and Windows, when the temptation was to port a DOS app straight over rather than redesigning it as a GUI?
If platform developers cared so much about consistency, they wouldn't change their UI design just to freshen up their image or because design trends have changed. Maybe looking and behaving like everyone else really has a major influence on user adoption, but it usually seems to be ignored in favor of branding.