If a $1800 16GB 13" MBP, with $100 of adaptors just to plug anything in, and $270 AppleCare, lasted eight years, you're paying $270 a year. That's the price if your luck is perfect.
(If you trade it in at 3 years and get $1200 then you can assetize the dock setup and that still comes to $290 a year.) (eta $230/y for the new M1 16GB)
For less than $270 I can go through a logic board repair on my 2012 every year this decade if my luck is horrible.
What was true in 2003 was not true in 2012. 2012 Macs will literally not be obsolete, ever. There's no OS that could overtax them unless it was designed on purpose to be horrible. They have sucky GPUs but that was just as limiting in 2012, it's not an issue of aging. That's why when you talk to an Apple Engineer about how 2012 Macs are just as good as today's, they say "T2 chip."