They even seem to think it is a good thing. But I don't see how not having a bunch of implementations that can't agree on the specifics of a file/interchange fo

They even seem to think it is a good thing. But I don't see how not having a bunch of implementations that can't agree on the specifics of a file/interchange format is a good thing. And being free and open is completely orthogonal. There are many proprietary formats that don't have a spec, and many open formats that do have a spec (like, say, json).