[gsich]

I wouldn't say it's a "decline". Most people just don't need an upgrade. You can use a PC from ~7 years ago for most stuff today. Gamers are not the majority here. The best performance boost you get from an older machine is a SSD.

[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.

[buboard]

unfortunately people dont use them. The best replacement would be is if someone made a popular home router that permantently runs an IPFS node or sth.