I was just at a Steam presentation yesterday. Those that don't know here, Green light is no more and now the process for submission is called Steam Direct. Steam is US Washington DC based with about 300 employees. Mostly, engineers.
According to the presenter, there is no algorithm to predict what will be a success or not. This is why they allow this kind of stuff to happen. Steam Direct will try to put some "controls" into the vetting system world wide with a concept they are working on called "Curators" - basically locating world wide specific moderators in foreign places to oversee submissions. They don't just host AAA, but the Indy sector....again good.
Within the question and answer session some voiced the grievance of poor games being submitted and they where told that some quality control would be coming (as stated), but we where told there is no preference/penalty/bias for choosing game engines and using them in the creation of a game. Which is probably a good thing.
PC SPECS: Windows 10 Home 64-bit, Intel Core i7-2700K (PASSMARK:10401.1), NVIDIA Geforce GTX 570 GPU (PASSMARK:5079.4) , 16GB RAM