Well, I've bought new Apple computers for over 20 years now and for the first 10 I had to replace them after a couple years because I couldn't run newer software on them but they were pretty much junk by the end of those few years.
The late `09 Mac Mini I'm still using has been a real workhorse though. I upgraded the Ram and Hard Drive about 5 years ago and it's still very capable for what I do. To be fair, the DVD drive died after just a couple years on it though and I didn't really use it much.
But I don't use Photoshop or almost any Apple software anymore (outside of the OS). I write code and I don't need much horsepower for that.
(Happened to me with a brand new Sony Vaio and a Dell, for example.)