They'd be hard pressed to justify bans when they knew about it for months and didn't address it. That's the thing. While the line between "exploit" and "creative use of game mechanics" is fuzzy, if you know about a problem and don't address it for a couple months (until it blows up on reddit), what message are you sending during those months?
More likely you see slaps on the wrist and not much else. Now, about that rampant botting problem...