No need to play games and intentionally be obtuse all across the thread. "They" are the developers. A website has far less access to a device than an app and ads are easier to block. So they wrap anything into an app to gain that access and make ad money.
What access?
Like the OS native APIs that offer the very utility for these apps to even exist?
Integration with OS features is what made the app ecosystem, because of utility. Project whatever conspiracy on that you want.