What exactly is an old Intel mac and what is a casual work?
For example, I have 2015 macbook pro. The last macos release for it is Monterey. Even brew has problems with that, erroring out when installing packages like libpng and complaining, that I should upgrade xcode cli tools. Which I can't.
Who is forcing you to upgrade?
For that matter, what hardware?
I run an old Intel Mac and it’s perfectly reasonable for casual work. I’m not paying for stuff like Adobe leases though.