While this would make the program more available for many, it would also be able to open the floodgates for quantity over quality, which is something that currently suffers with Unity and Steam (Unity is an amazing engine, though. All you need to do is look at games such as Yooka-Laylee).
There is a chance this might not happen. It's a hard choice to what could happen. Would Stencyl sell? Would Stencyl become more known for quantity over quality? It's pretty much a dice roll with Steam, and having your product on Steam doesn't mean much nowadays, as there's a large amount of shovelware on the storefront recently (Most of Steam's new games in 2016 were shovelware, which caused the creation of Steam Direct, and the end of Greenlight)