No rule is inviolate
in 3.5 those things were so freaking scary that you made sure the answer would probably be no at any level. in 5e they are harmless
Yeah, they dumbed down a few monsters more than I'd like in D&D, though the 3.5 version = nasty. Still, if properly run, the first time one of those ghouls in a pack managed to paralyze someone (solid chance with low level characters), I'd be having them all turn on that character. 2 hits when down to 0hp is autokill. There's no logical reason they'd be stupid or forget their eternal hunger to be "fair."