Soldered chips are just easier to design.
Once you get connections involved, impedance matching and tolerances etc, become far more difficult to design and manufacture for, at the expense of the amount of waste when something fails.
Once optical chip interconnect becomes mainstream, (its already in high end servers) the problems of impedance matching and interference almost disappear making separating the ram and cpu again a reasonable approach.
The high RAM speeds are much easier to achieve soldered. Even the air gaps of pin and pad connectors make for unreliable speeds and therefor instability, at these speeds.
This is exactly why I’m so on the fence about getting the desktop (or other mini pc) despite knowing that the form factor fits my current lifestyle better than my laptop. Hard to decide if the upgrade is worth the lack of cheap repairs/upgrades.
For traditional desktop PCs, socketed CPUs are still the norm. In compact systems like the Framework Desktop, soldered CPUs allow for a smaller design, better power efficiency, and support for faster memory, but they sacrifice CPU upgradeability and make some repairs more difficult.
I mean you can massively outperform the memory bandwidth on strix halo with socketed setups, it’ll just use (a lot) more power and be quite a bit more expensive, both intel and amd are up to 12 memory channels on server cpus now.