Re: Don't get it
A parallel interface seems like it should have a higher bandwidth, but keep in mind that all those connections must be electrically isolated and synchronized. You have to route connections for 300 pins for DDR5, and try to keep each path roughly the same length to keep the signals in phase (plus same inductance, capacitance, and characteristic impedance).
Increasing the speed of one transceiver is easier than speeding up parallel transceivers while keeping them in lockstep. This is why USB has replaced older parallel connections for keyboards, mice, and printers, and why serial SAS replaced SCSI for disk drives.
Biting the hand that feeds IT
