More likely because Necromancers are given to weak players who are unable to take advantage of their strengths. I recently watched Pit-Vitalik's save from the "Necro vs. Flax" tournament; in the first week, Pit, playing as Flax, gathered something like 250 skeletons with just one Vidomina. And on day 123 or 124, he already broke the Guardian Order, without any angels or vivs, just skeletons with minimal help from native troops.
Pit-Vitalik: http://heroesportal.net/tavern/?id=258389&pagenum=3
Week 1 - "Gathered 200 skeletons."
On day 127, Vidomina (21, 2, 9, 7 (70)), 5 angels, 400 skeletons, 27 storms, 22 ice elementals, a hundred of griffins, and 5 fire elementals are again at the Guardian Order. On day 131, I fly past the Guardian Order, see Galtran rushing, and his skeletons nearby.
Necromancers are very unstable - I played against one top player, and he took three restarts and still couldn't start as Galtran - unplayable matchups. Plus, I played against Paladin and LeBrom, and they both lost playing as Necromancers.
Please, let's not put everyone under the same rules and treat them the same.