I suspect this is the case for a chunk of that $10B.
Really not impressed with the whole ecosystem and will not be investing further in it.
Edit: to clarify. They didn't buy the apps, I did. No in app purchases were made at all by anyone. The reviews are hopeless - unlike amazon for example there are no reviews or ratings of the reviews so you cant determine the difference between idiot reviewers and idiot developers until you've paid for it. Ad blocking is to stop the piles of malicious and idiotic pages forcing popups and apps down on you like its 1998 again. User alexpenny found a reference to this below - thanks: http://techcrunch.com/2014/01/06/shady-app-install-ads-are-a...
Edit 2: it appears HN has limited my efforts to defend myself in replies...
Edit 3: this is happening only on iOS devices. I don't have any android devices. This does not happen on any of my desktop machines running Firefox + AdBlock Edge. In fact I get no popups or install attempts at all and never have done.