>>96827248
No.

Don't get me wrong, they're as much of a threat as you would expect a massive, incredibly advanced empire to be. But the reason Chaos is the big bad is because the call is coming from inside the house. You can spot a Necron from a mile away, but Chaos could be living in the hab next door. An entire planet can fall to Chaos without the greater Imperium noticing until it's too late.