[aesthesia]

Desktop sales were already declining 7 years ago. A lot of people just don't care to have a desktop PC any more, and when their old computers finally break or stop working, will replace them with laptops or tablets, which can't do the sorts of always-on distributed things that we might hope.

[gsich]

I would count Laptop to the PC category. Same year span - have a Laptop/PC from 2012 and you are good to go.

[rspeer]

But the key difference remains: there aren't many personal computers that we leave plugged in and turned on 24/7 anymore.

[gsich]

This was never the case.

[buboard]

That was and still is the case. We just have forgotten about it. In the past it was SETI/napster/torrents/kazaa etc. Someone else mentioned minecraft servers. There are also lots of people running similar opensimulator servers at their home. Unfortunately laptops/tablets have thinned that crowd and the possibility of having such arrangements is smaller overall now.

[r_c_a_d]

I presume you mean "never the case for many people". As in "most people never left their PC on 24/7". That may well be true.

I used to run a couple of minecraft servers for my kids. Judging by how amazing their friends thought that was... I don't think there were many other people in the town doing that.

On the other hand, I still have a raspberry pi running 24/7 to this day.

[gsich]

Yes, but in this case your PC is doing something. It has a purpose. 24/7 without doing anything is a waste of energy.

[rspeer]

Of course it was the case. What do you think things like Seti@Home were running on? People who owned computers had so many idle processor cycles that they were desperate to find something to do with them.

If 24/7 home computers were never a thing, what did BBSes run on?

[gsich]

Same answer: Yes, but in this case your PC is doing something. It has a purpose. 24/7 without doing anything is a waste of energy.

[rspeer]

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).