1. Linux isn't a panacea for depreciated hardware, and it never will be.
2. If your priority is system lifespan, you are already using OEM macOS.
Never said it was “panacea for depreciated hardware.” I’m saying it’s a common use case.
Every thread about Linux inevitably someone says “it gave new life to my [older computer model].” We’ve all seen it countless times.
1. I dunno about a panacea, but it's pretty great for old hardware. My 2011 desktop still runs Alpine Linux just fine.
2. By all means start with macOS, but eventually Apple will stop supporting your machine. And y'know what will still work and get updates then? Linux.