I agree it would be great for users to be able to mix and match EDA tools, but EDA tool vendors seem to disagree, and consider the state of poor interoperabilit

I agree it would be great for users to be able to mix and match EDA tools, but EDA tool vendors seem to disagree, and consider the state of poor interoperability among EDA tools as a nice barrier to entry. As far as I can tell open source tools work on bitstream generation because it is unnecessarily painful to interoperate with proprietary tools.