Yes, we've come to expect this now. But it's completely artificial. Developers stop supporting iOS because there are newer versions of iOS.Lots of bank applications stop working on older versions of iOS or even just older versions of the app itself on current iOS versions. They require that you update to sign in. Email providers do the same. So older devices lose some functionality that many consider basic, simply because they cannot install a more recent OS.
If they stopped releasing new iOS versions and just focused on minor updates, older devices would last years longer.