From my limited understanding, the specific performance benefits in the article come from it being DDR5X memory. LP (Low Power) DDR needs to be very close to the CPU (short traces) because of how much less power it consumes. DDR5x should have the same bandwidth as LPDDR5x, it would just consume more power. Up until now, there wasn't a way to have "socketed" LPDDR, so it was soldered to the motherboard or even placed in the same package as the CPU (Apple M-series CPUs have the RAM in the same package as the CPU). Now they have a standard way to basically strap down a BGA chip that will live right next to the CPU.