Large groups of people all contributing small amounts towards a goal none of them could accomplish on their own is the only way any of those things ever get done.
I could be wrong but my understanding is that 24/7 dedicated servers are wildly economically unviable. The reason cloud tends to cost less than local today (other than the subsidization) is because you aren't running models 24/7. So like 6 hours of cloud per weekday might beat the yearly cost of building local machines, but it's not in the same universe if you're running 24/7, as evidenced by two months of H200 rental costing more than the DGX Spark this Laptop is built out of.
Except that's the point. It is the same store. It is two different cashiers. The second one doesn't know you got the ID from the first one, that's why it works. The point is that if a store like that existed, it would be stupid as fuck.
Also, at least in ChatGPT, it has access to every other session, so you're never working with zero context unless you create a new account (and even then they could have other fingerprinting, I just haven't tested it).
If everything that you know about the world fits in a 2km radius around your house, you aren't doing anything.