I think you might misinterpret what happened to Zynga. In my opinion, Zynga did a great job building on top of Facebook and building independent games that had deep retention. Unfortunately because they did so well on Facebook on the web, it feels like they missed winning the same shift to mobile. Other companies in the early Facebook platform era like Slide or RockYou were larger than Zynga but didn’t have as clear a path to being adjacent or independent from Facebook. The bummer for Zynga was less when Facebook got more challenging to build on (they were already so big) as when new game developers started making more $ on mobile