Then those people are liable for defamnation. They are not if I change what you wrote and gave explicit permission to do so.
If and only if you gave permission to attribute incorrect statements to you, surely?
Yes, and the GPL does this, and so does the GFDL in non-invariant sections. Hence the need for verbatim-only sections.
In general, copyright and reputation are two mostly independent things and rightly so.
Sure, one is law, the other one isn't.
For example, I consider having to print the adverts ("invariant sections") with a subset of the work painful, to the needlessly wasted trees as well as me. Generally too much pain, like using BSD with the obnoxious ad clause code, but worse.
Your comparison doesn't make sense, the old BSD license is for software, the GFDL is for books, manuals, etc.
You obvioulsy don't get the difference between non-functional and functional works, please try and figure out why they are different before continuting with these comparisons.
You obviously don't get that your distinction is entirely arbitrary.
The same can be said for you who consider them the same.