I think the rub here is that most developers aren’t developing/publishing their own software, but honing their skills on writing proprietary code while also putting food on the table. To that end, a permissively licensed library is better because the company will actually use it and the developer will gain experience with it that they can then use outside of the proprietary environment to contribute to FOSS projects (some of which may well use GPL). If a GPL end user product gets popular enough, it will eventually be able to use all of that gained experience to compete with the propriety alternatives, so I do think the two can work in tandem.
I find this kind of baffling, honestly. Like I’ll follow this one to see how reviews turn out, but superstars was by all accounts what people had been asking for. So they released it and… that’s it, no updates for more characters and maps, not even as paid DLC. Why didn’t they do more development on it?