Can Necromancers even be defeated?

Isra and Vidomina are weak heroes because they only start recruiting skeletons at a rate comparable to other necromancers with expert necromancy after level 10. However, during the first 1-2 weeks, the game involves fighting numerous but weak units, and you need to immediately recruit 30% skeletons instead of 21%. Considering the common strategy against necromancers (a rush), specializing in Isra or Vidomina simply won't pay off in time; it's better to choose Clavius or Tamika.

To be honest, I've never liked necromancers; I only like vampires and liches. I usually play as humans or the Underworld faction; I like them more. Regarding whether it's possible to defeat a necromancer, my friend really likes them, but when he plays against me, he almost always loses.