I guess, Jason, Michael, and Freddy all came after Leatherface and they are the sole antagonists in their films. What Leatherface is is something else entirely. I think the other three have a lot more in common and are part of the Slasher movement while I think Leatherface and TCM pre-dates it and is something else entirely.
Though I guess you're presenting a position of "Zombie Redneck Torture Family" vs "Zombie Redneck Torture Loner" being two completely different species. Well, it at least gives a clarification on the answer as to why you feel it's different (and I did ask for your 'why' earlier)
(And re-reading back, Iroquois, also gave a very similar response earlier that I just blurred these two posts together in my head).