So at some point your choices will be to either use a potato (often with a locked bootloader) or muddle through as best you can with an old phone that cease receiving security updates, including kernel updates, in the very near future.

It's the same forces that decided all TVs should be "smart" and have made dumb TVs difficult and sometimes expensive to obtain, especially if they are of any quality. The manufacturers want you to buy whatever drives their own and their partners' profit margins, and the buying public is too apathetic to care.