Honestly, the idea of upgradeable RAM was purely tied to it being low-speed, high-cost devices. This in turn drives the ridiculous markup some companies charge now, drives up system costs due to complexity, and harms performance.
Having a desktop CPU with integrated 64-128GB of RAM would probably justify the lack of "upgradability" with sheer performance and power improvements. There was never much upgradability there anyway - you could start by underspec'ing and then later fill it up to the (surprisingly not that high) limit, but what you saved by not buying all the RAM up front is probably less than the extra cost for supporting it at all. Paying more than the cost of RAM to have the flexibility of not buying RAM.
(Phones have 24GB of RAM nowadays, a PC should not have any less than 64GB of RAM as base tier.)
Having a desktop CPU with integrated 64-128GB of RAM would probably justify the lack of "upgradability" with sheer performance and power improvements. There was never much upgradability there anyway - you could start by underspec'ing and then later fill it up to the (surprisingly not that high) limit, but what you saved by not buying all the RAM up front is probably less than the extra cost for supporting it at all. Paying more than the cost of RAM to have the flexibility of not buying RAM.
(Phones have 24GB of RAM nowadays, a PC should not have any less than 64GB of RAM as base tier.)