Maybe not anymore but the app store was launched in 2008. If you look at the percentage a writer or a band makes from a physical book resp. studio album, 50% actually looks very optimistic. Don't forget, there were multiple layers involved, including shipping, wholesalers, retailers, etc. and everybody wanted a cut. There's a reason desktop software to this day has a much higher price anchor than mobile!
My point was that "distributors" or retailers never took 50% as the original post suggested.
If you believe that the reason desktop software has a higher anchor price point than mobile is the multiple layers, please explain why the price point on the Steam store is so much higher than the app store.
Your Steam analogy is flawed due to selection bias - Steam is about games, and games are more similar to movies than apps. People want entertaining content (and a good amount) for that initial price.
Does Steam allow for freemium? What about ad-driven games?
The mobile carriers often charged upwards of that rate to game publishers.
You are crazy if you think this is a way for Apple to do anything other than capture some of the existing market of app ads, which has been incredibly lucrative for Facebook. They have so many ways to get more information about how useful an app is likely to be for you that they don't use, they don't need another signal.