There's an (unverified) myth that retention on mobile apps is better. This is one of those things that marketing people keep telling each other without ever verifying the facts. (Unless you deliberately make the web version inferior, of course.) The reasoning behind it is that you should take real estate on the user's home screen at all costs, because your app's icon will serve as a reminder and people will allegedly…
Why are you calling it an unverified myth? In reality there are petabytes generated everyday proving the efficacy of mobile apps vs websites. This has been tested and measured in pretty much every possible way at this point with 100s of billions in ad spend. It's not just real estate on the screen, it's faster on-device processing with lower latency, rich offline abilities, better and more persistent access to more A…
More often then not, the front end devs responsible for the app are not very good with "normal" web frontends - so they sabotage the competition, to reduce work. Also, web pages, could be repackaged into Apps by others leeching from the products attention.