My understanding is that the FSF requires copyright assignments in order to give themselves the ability to most effectively defend the community against poachers and legal attacks. It would be a drastic misunderstanding to think they do it in order to give themselves an ability to share that they'd deny to others. The FSF's fundemental value is to give everyone the ability to share, even (or perhaps especially) in the absence of copyright assignments.
> ... the FSF will never have a problem, because it demands copyright > assignments for all contributions. Although this might be true it is irrelevant, as given copyright assignments they would not have a problem even if they used a proprietary license. Furthermore, since assignments are just a matter of expedience, under appropriate circumstances the FSF might well incorporate materials without an assignment. That would be their call, but I cannot imagine it is something they'd want to rule out unconditionally. If the GFDL is impeding sharing, there is one thing we can be confident of: that the problem was not anticipated when the GFDL was drafted.
