I can see how the wiki can be a collaborative effort. I can see how some might be offended by such, yet improvements are one thing, and deletions without replacing with anything significant are another.
Its more a matter of writing being a waste of time and energy, if whole portions are deleted, with nothing of any significance replacing it, and I've seen that occur. Why spend time writing something when it just gets deleted on the wiki, but gets left alone on the forums or the website.
And discussions are fine, but when things aren't discussed, and different contents are changed because one person sees the wiki as one thing, and another person sees it as something else, how's the resolution to really occur? Creative time and energy becomes better spent in other ways.