Some people consider the GPL a non-free software license. I fail to see your point. The GPL is a free software license, and the GFDL is a free documentation license (not because it is a documentation license, but because of the rights it gives to users).
I do not object that the GFDL is a free _Documentation_ license, but I'd say that unfortunately it is a bad license, it has many problems, and there's no need to conceal them and fight against any criticism like it be a matter of faith.
Please state what these problems are then, I don't think anyone objects to having a discussion about any problems the GFDL has (I even think that it has some problems, but invariant sections are not one of them; the major problem with the GFDL is infact that it is far to long and to complex so one can grasp it correctly).
Nobody is concealing them, or is fighting against any criticism for the GFDL. The problem is that some people simply have the wrong starting point, just like people who consider non-free software something that is morally and ethically correct.
Also, it would be nice if people stopped saying `the GFDL is not a free license', this has absolutley no meaning whatsoever. I too err on this. It leads to a massive confusion over what one is discussing since it implies that there is a specific set of freedoms that apply to _all_ works, a set of freedoms that is always the same no matter what one discusses. It is a clever tactic that is used exessivley by those who try to convince people that the GFDL is suppsoedly a bad license, much like calling treacherous computing for `trusted computing'.
And please stop this flame,
This is just a heated discussion between hard headed hackers. If you consider that a flame, then you are not capable of having any discussion about anything one has a passion for.
Cheers.