[kijin]

> So I'm stuck in a bind, with no other option than to throw this (perfectly good) machine out completely.

No, you're not. The next logical question would be: "So why don't you get a different OS?" There are dozens of FOSS OS's that will work just fine on your machine.

Apple is well-known for its rapid cycles of planned obsolescence, and technical users have no excuse for not knowing this. Either you keep buying their products on their schedule, or you say goodbye to their ecosystem. If you do neither, you have nobody to blame but Apple and yourself.

Why should Reddit keep supporting a Firefox version that was EOL'ed over three years ago and is known to be grossly insecure, just because Apple and you disagree about which Apple devices Apple's OS should support? That's a problem between Apple, Mozilla, you, and nobody else.