This has somehow turned into your opinion on energy use (yes, it's good that desktop PCs can now decrease their energy use significantly while idle, which was not the case in the 90s).

But you made a claim that "this was never the case", when clearly there was an era of home desktop computing when your desktop could act as a hobbyist server. This era gave rise to BBSes, then MUDs, then Minecraft servers (and many things in between).