Their site, their ToS, their rules.

While this news is sad to me, it's not something to complain about IMO.  there exist many other ways to buy and sell btc for fiat, and while they were becoming popular, Coinbase or any one method of exchange restricting gambling should not rustle the feathers too badly.

While I can't help but ponder what Coinbase considers "gambling" or how easy it would be to mask what you are doing with your bitcoin, I would not try to deceive them & their ToS, as it seems that would put funds at risk. 

An every-changing landscape no doubt, Bitcoin ATMs & Mycellium local feature are likely the big winner in this.