come_from_away wrote:
It's called competition.
If competition alone was sufficient to get developers to support apps on old/obsolete hardware and operating systems, the developers would be doing that already. They obviously aren't.
If anything, competition is what's driving them to abandon support for old phones. Every dollar, or hour, spent developing code for, or supporting, old phones that are not providing revenue for the developer is a dollar or an hour not spent developing code for, or supporting, new phones. In effect, new phone and old phone owners are competing for the developers' attention. The owners of the new phones are making a more attractive, and more competitive offer. Because the owners of the old phones are not making a competitive offer, or at least have not convinced the developers that they are making one, they lose the competition.
Even Free Software / Open Source developers do not support old operating systems forever. Sure, you can get source code for Firefox or LibreOffice and try to port it to old versions of macOS yourself, but the developers of both of those projects now only provide pre-built binaries for macOS Catalina and later. If you are still stuck on, say, High Sierra, tough for you.