If such whimsical lawsuits are indeed a possibility, then the danger of action should be weighed against the danger of inaction: right now, any past contributor could sue for violating GFDL 4.A, failing to change an article's title after modification. I just don't see how suits like that are viable.
--Axel
What do you mean by "Article title"? We do provide an article title which changes with every edit. Click on "Permanent link". It's also availabe with the author list. The GFDL itself recommends adding an unique number to the end of a title section to make it unique (section 5).
Also, you would also need to prove that you didn't gave permission to keep the title when abiding to Wikipedia rules: "You may use the same title as a previous version if the original publisher of that version gives permission." If we consider that the publisher are not you but the Wikipedia project, the case is even clearer.
You've got the burden of proof backwards there. Once the person suing for copyright infringement establishes a prima facie case for copyright infringement (that they wrote the text and that you copied it or prepared a derivative work from it), the burden shifts to the defendant to prove that they have a valid license.