Each trade is like stocks. Rewards are income.
It's different from WoW because, as far as I know, WoW is not traded on regulated exchanges. Steem also (obviously) isn't going to get hit until after the market-cap leaders.
It's counter-intuitive but it would be better if the IRS just starting taxing BitCoin and making the rules clear. I think that the uncertainty is hurting wide cryptocurrency adoption more than taxes will.