Different kind of compression than you are probably thinking about.

It's a compression-attached connector, like a CPU socket, instead of an edge connector like DIMM.

CAMM was made necessary because SO-DIMM could no longer support the kind of signaling that next-gen memory needs. CAMM allows both for much cleaner signal paths, and for more signals.

It's coming to desktops too because there is no sensible reason to have a separate desktop memory standard. The split between DIMM and SO-DIMM only exists because SO-DIMM is worse, and DIMM is usable on both servers and desktops. CAMM2 is better than DIMM, and servers have mostly moved to different, incompatible memory types anyway.

Ooooh, okay. I was thinking of something horrible, like DisplayPort DSC… but for RAM, because in aggregate that would need less bandwidth and less pins.