According to Froogle, Dovetail wanted 30% from 3rd parties developing for FSW. If that is true, then adding the 30% cut from Steam would have left 3rd party devs with 40% of their products retail price. It would seem that Dovetail priced FSW out of the market for support by 3rd parties.
Have you got a source reference? It was my understanding Froogle died out 10 years ago. Why is it relevant to use data from defunct source of information?