That's splitting hairs. It's not part of the HEDT platform, but AMD sells Threadripper CPUs that have both 12 and 16 cores. Are those not HEDT CPUs either?The 5950X isn't an HEDT CPU.
It's an option for people who might need additional lifting power from more cores but don't want to invest in an HEDT system. Most desktop users won't get much added benefit of using a 5950X over a 5800X.