I certainly get your meaning, but that doesn't sound like Apple's fault. Could they have made it backwards compatible? Probably...but they also don't support an OS more than three versions back. ¯\_(ツ)_/¯
As for useless......I'm still running two 12 year old Macs that were purchased new. The iMac is on its second hard drive and requires a video card swap to update beyond High Sierra. Doable, but not for the faint hearted. The Air went to Monterey without issue. It runs a little hot, but loading a 2 year old OS onto a 12 year old machine? I'm surprised it runs at all.
In comparison, Windows machines tend to not age well.
Turn of phrase Ruefus; We tinkerers find a way . I baked the graphics card from my iMac twice to re-flow the soldering before it finally gave up the ghost due to the massive amounts of heat that thing generated. I'm still using the screen from that machine to this day. Macs are built like tanks but I think the new MO for apple is to release as many tiny updates to the kernel as possible so that none of the hardware can (officially) live it's full lifetime.
My comment was really referring to the keyboard and trackpad that will soon become paperweights rather than remaining useful for a few more years.