> I don't understand how a "free" thing can be anti-consumer.

Not 100% apples-to-apples, but I imagine you've heard cases of "big players" in various industries lowering their prices to the point of selling at a loss, which drives out the small players (Amazon, Wal-Mart come to mind). In the end, only the big player is left, and they are now free to raise prices.

I think it's reasonable to see that initial low-prices (could even be free) period of behavior as anti-competitive, since it may ultimately stifle competition in the long term.