for another, devs are definitely making the web experience subpar which has been mentioned elsewhere in this thread. most websites are just adverts for their apps if they function at all any more. loading a website on mobile is even worse than desktop as they pester you with "it's better in the app" pop ups.
people find browsing an app store much easier than browsing the web. in fact, do people browse the web at all any more. search is shit now, so discovery by search is not what it used to be. click through from search is also plummeting as "search assistant" type responses means no reason to click through to sites.
how many more reasons do you need?
One. Because I don't believe one exists. The reasons you gave of it looking nice and accomplishing something the user wants to do provide value to the user.