It's almost as if there's collusion with some app developers & . Lots of free apps are pushed when visiting websites yet the website has all the same or often more information. Often the app is just an abbreviated formatting change which provides nothing useful compared to the website....
Apps typically get updated regularly (whether they need to be or not) and often when a new version of iOS comes out, the app's minimum requirements jump up a notch, deprecating earlier iOS versions that used to run perfectly fine.
Over time, eventually, an updated app will no longer work at all on an older iPhone that CANT upgrade to a newer iOS version, so the only choice available if you've become addicted to that app is TO BUY A NEW IPHONE.