> There's a decades-long meme that Apple purposefully slows down older hardware to push people to buy completely new hardware.

I seem to recall the first several years—maybe even the first decade—of OS X being marked by each new release being faster on the same hardware, though dropping support for the oldest hardware. It was definitely true for the first few releases of OX X, because 10.0 was notoriously sluggish. I also don't recall any slowdowns with my 2006 iMac across the several upgrades it received before Apple made 64-bit firmware a hard requirement.

If there's any truth to the meme you cite, it probably stems from the mobile side of things, where iOS started out fairly efficient but the hardware was very underpowered. (And in that case, I'd like to point out that the iPhone is only 10.5 years old.)