> Quad-channel RAM is common on consumer desktops

Yes, but tablets, laptops, and normal (non-HEDT) desktops have 4 channels, 4x32 bit = 128 bit wide. Modern memory with DDR5 allows two 32 bit channels on a 64 bit dimm. The previous gen DDR4 would allow 1 64 bit channel on a 64 bit dimm.

So strix halo (on laptops, tablets, and desktops) allows for a 256 bit wide memory system, providing twice the memory bandwidth of any ryzen or intel i3/i5/i7/i9. The Apple pro (256 bit), max (512 bit), and ultra (1024 bit) lines of apple silicon have greater than 128 bit wide memory systems. On the AMD size it's just the Threadripper (256 bit) and Threadripper pro (512 bit), but those are typically in expensive workstations that are physically large, expensive, and need substantial cooling.

So the HALO is pretty unique (outside of Apple) for providing twice the memory bandwidth of anything else that fits in the tablet, laptop, or small desktop category.