While I'm sure that there a few "devs" whose alleged projects are scams through and through - that is, the project was never intended to be finished; a promising start is used to secure backers who are then fleeced for as long as possible - there's no way it's the majority or even a significant minority.
Creating enough of the rudiments of a game to inspire people to throw cash at you takes some degree of talent and passion with no guarantee that anyone will support it. As scams go, it's a terrible model. What you want from a scam is minimal start-up effort, with work only being put in once you get a bite.
To take this game as an example, Inno's put in way too much work for this to be a premeditated scam.
