Two sides to the issue. FCBs are good thing for existing homeowners in Irvine since it boosts everyone's home prices. Not so much for people looking to buy. But then, back in 2004-06, there were domestic buyers bidding up the prices. You can't blame FCBs. You can blame BUYERS in general that bid up the prices and price out many house hunters. Such is the life, everywhere with everything.
The FCBs that buy and immediately rent out the place do somewhat negatively impact the local economy over period of time. Over years, as opposed to owner-occupied home, that investment property owner won't be spending as much on the upkeep/upgrading of the home, and neither will renter.