That is, assuming that anyone actually uses Lumberyard/GameLift. (Do they? Can anyone name a nontrivial game?)
The AAA scene is using their own engines or the unreal engine. While you can switch engines when creating a new game the incentive isn't there when you either already have licenses for the unreal engine and a small army of programmers who have mastered it.
People were expecting a shit to Unreal when they decided to make it free for education/take a 5 % cut. This shift hasn't happened...
https://steamdb.info/app/252850/graphs/
The game was free until November 18th 9am PST, so the current active ~100 daily players is more representative of its success.