They don’t see a problem with their own app, so why would they? They’re killing the 3rd party apps so they can have more control over what the user sees (ads, gold, avatars and anything else they can make money with). They can do that with the official app (which was already a 3rd party app they purchased), no need for Apollo or any other 3rd party app anymore. They feel like their user base is big enough that it will sustain itself without the 3rd party apps bringing in free users.