Just because the latest OS isn't able to be installed on older hardware does not mean the hardware in no longer usable. I know people to this day that still run the last 2012 cheese grater MacPros with Snow Leopard as daily work machines. They still use Final Cut 7 on them to capture content from tapes. At this point, they are very fancy dedicated video recorders, but they still run and are money making devices.
You're right; I still have a 2010 MBP w/8GB of RAM and a SSD upgrade I made to it years ago. My mother still uses her similar vintage MBP with the same upgrades. These work just fine for most non-work tasks.
That doesn't mean that I expect these things to be updated or supported 15y after I bought them. I am absolutely certain I made the back $850 I originally paid (edu discount) + the ~$250 in upgrades over the years and I'm entirely ok with just letting it limp along until it physically dies. I think most people have similar expectations.
I still have my 2011 MBP with very similar upgrades, but unfortunately, it has the known bad Nvidia GPU that has been repaired multiple times. The last time it was taken in for repair, Apple said they were no longer supporting the repair. It's still usable as long as nothing tries to access the GPU, but as modern web tries to use GPU it would crash the laptop constantly.
Lucky you, so to speak. Back in the day I had the same one, but it would pass their diagnostics, so they wouldn't repair it, though I could literally make it crash in front of the Genius Bar techs reliably and repeatedly (essentially the same way, by trying to do anything that hit the GPU a certain way - websites, Photoshop). "Sorry, our diagnostic tool says it's not the GPU". At one point I even demanded they do a completely fresh install of the OS. On first login, I fire up Safari, go to a certain site, crash. Restart, go to a different site, crash. "Sorry."
I liked out in that mine never developed any issues with the GPU itself. Though it was stolen in 2014, so who knows longer term. My daughter is still running my (iirc 2014) model. I've been relatively happy with my 16gb M1 Air, aside from my own vision issues.
The last security update for Snow Leopard was in 2013. Friends don't let friends connect software that vulnerable to the internet.
The hardware can be ok, the walled garden is not.
Production networks like these are typically not on the internet. That's a bit of information that I take for granted that people not familiar with would not.
What does this have to do with typical consumers who purchased a 2023 Intel Mac only getting 5 years of security patches? Typical users connect to the internet.
“Those systems will continue to receive security updates for 3 years.” - looks like 8 years in total.