My guess is that Valve did allow it, but now doesn't. It's probably not a coincidence that that these new free to play games appeared at the same time Valve dropped Crysis 2 from Steam. They likely tightened up their terms to prevent companies from bypassing Steam, much like Apple has in the past with their App Store.I think this is the problem. The PC version can sell DLC from within the game itself. I doubt Valve allows this, which is why they never carried free to play games until they started using Steam Wallet for the DLC microtransactions.
Ehh... We have no idea what the agreement between Valve and EA and/or Crytek actually said or says, so I don't know how he can say it's been "clearly" violated.Here's a good post from the thread I linked to IMO.
I suspect this will be regarded in hindsight as Valve's first small step down the road towards becoming their own "evil empire". Only Apple and Microsoft, on the Xbox 360, have gotten away with setting terms like this.