Three points leaves to much flexibility to a necron player. He can march to the opponent's base and keeps a cap margin to prevent an attack on his base.No, I didn't build nothing but banshees. I had warlocked guardians backing them up. I didn't have the economy to build reapers, despite the fact I had all but the 3 points around the necron's base capped. See, when you are playing as Eldar, you really have to make a choice...it's either banshees or reapers...not both. If you try building both, it's suicide. Your tech and economy get slowed down considerably.
Competiting for the SP points allocated to the necron is the must be done in tiers one.
Later fire dragons and an eldar tank dedicated to back stabbing into the necron when the necron decides to march can warrant that the necron player has to fight to maintain his flexibility.