I've never found Daemons to be particularly broken. They have some powerful units, but every army does. It's possible that you're just a better player than your opponents, so you win. It's also possible that you're taking the game too seriously and using the "I hate fun competitive" lists that are awfully hard to lose with if nobody's on their A-game.
Now that I think about it, I don't think I've lost to daemons with my Warriors of Khorne. Even though you're unbreakable, daemons still can lose combat, and if they do, they take casualties, which makes it harder to win subsequent rounds of combat.
I've found a handicap in points ultimately doesn't mean anything in WHFB. A unit of Warriors of Khorne, for example, can take on about three times their points' value in goblins and come out on top. Cutting the Chaos player's points allowance doesn't mitigate the fact that a Warrior of Chaos is just a far better model than a goblin.
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