Tactics for playing against a Necromancer.

It would be great if someone could simply write in detail why (and at what stages) other factions are not competitively viable, what possible builds exist for them, and what counters are available. Also, explain why these factions can only survive. For example, I often easily defeated a Necromancer playing as Elves. Humans and Elves often have Divine Might. And so on, and so forth. I'm not asking for an argument; I'm asking for specifics. Then, a newcomer visiting the forum will see something useful, rather than just a bunch of vague statements. For example, they go to the forum and read: "Dwarves are stronger than Humans" (hypothetically). What will this teach them? Nothing, right? That's the kind of situation we have here.