I think it's a bit broader than feeling dumped by Apple...
There's an entire generation of old techies who grew up with modular desktop machines. Either Mac or especially Windows. You got your minitower machine, added some RAM, added an expansion card for some new connectivity technologies, maybe added a processor upgrade (those were more common in the Mac world than in the Windows world), added a hard drive or two, upgraded the GPU, etc. Kept it going for 3-5 years, spent lots of time and very hard-earned money (because, well, younger folks made a lot less money) upgrading it, then finally finally managed to replace it with another.
In Windowsland, other than home-built machines, the best example of this were the built-to-order machines that made Dell/Gateway in the late 1990s. Intel motherboard with no onboard anything beyond IDE/parallel/serial, you got a discrete graphics card, a discrete sound card, a discrete modem, a discrete network card pre-installed in your PCI slots. Those machines look so weird today, coming from the factory with potentially 4-5 slots used. You could pick one of several selections for all of those components (all fairly high quality), your storage, etc, they'd assemble it and ship it to you, and you could just replace any of those components later if you wanted.
In Macland, I would probably guess (not having been on the Mac side at the time) that the peak of this era was the B&W G3 and the G4s. Affordable entry price, no built-in video, lots of PCI expansion options, a world that was moving fast with new connectivity technologies and new drive types, etc. The G5 started to up the price and move more workstationy.
And the last gasp of that type of machine was the 2010 Mac Pro. A little too expensive and workstationy, but it was still a modular half-affordable desktop in a way that nothing that followed was. The trash can, by contrast, previewed the philosophy that has now given us Apple silicon.
As much as it pains me to say it, that era is dead. Even Windows gaming land has abandoned modular machines - most modern gaming cases have no drive bays, few open PCI-E slots except the GPU's, etc. Sure, this is a little more modular than the modern Mac, but... not that much. Not compared to what it was two decades ago.