There are many things in play here. 1. Platforms only ever allow one version of an app to exist, and its requirements can only reasonably go up. (e.g.: want to

There are many things in play here. 1. Platforms only ever allow one version of an app to exist, and its requirements can only reasonably go up. (e.g.: want to use the new Swift feature? you need to target iOSN+1) 2. Most apps now have cloud components. Maintaining old version with evolving backend APIs is a huge pain. One could of course version their API and keep the old version working for a long time. 3. User expectations have changed, if you haven't updated your perfectly working app in 6 months, they consider it dead and move (I don't get this, but it does happen). 4. Tons of apps are made by small teams or even single people. Maintaining a version that is compatible with all devices is a soul-crushing job. This is also why apps from gigantic corporations usually have better old device support. If 1% of your users is 100k+ people, it's way more lucrative to keep them happy.