It’s clearly for data collection. Take the yelp web app for example. It used to be much nicer than the native one. Then, they intentionally defeatured it until it was useless.

Also, this situation benefits the google-apple duopoly, since it means superior products (remember Windows Phone 8?) or privacy focused devices (FirefoxOS) have no chance of getting a foothold in the marketplace.

The objections I see in sibling comments are nonsense. Modern web supports high frame rates, developer control over the UI, etc, etc.