But the lack of a replaceable CPU need not doom DIY. I have a 5+ year
old DIY PC that I am considering upgrading. But since I want USB 3.0 ports,
that means I have to replace the MB anyway, and probably the case to get
external USB 3.0 ports. And maybe the disk drives to get the latest
high-speed drives there, and of course memory, to get the best.

The point being, after a couple of years, lots of things have to be
replaced, not just the CPU.
--
The first requisite of a good citizen in this republic of ours is that
he shall be able and willing to pull his own weight.
Theodore Roosevelt