My less-techy relatives are routinely forced to upgrade because all of their apps drop support for their hardware.
I'm in the process of replacing my nephew's tablet, because his favourite apps (Audible and YouTube) can no longer be installed on Android 7 - the newest OS his hardware can run.
My mum bought a second-hand iPhone 8 a couple of years ago, because the battery in her iPhone 4s finally died. She'll have to replace that soon, though, because a bunch of critical apps (her bank, health insurance, and a few others) no longer support that screen resolution properly, and often place buttons outside of the visible screen area.