Rule of Cautious Editing Judgment
Ninety-nine percent of the wiki's users are not looking for a fight.
You're editing an article, perhaps on, say, the pop-culture assessment of America. On seeing a description of the negative stereotypes that pop up, you decide to add a past President as an example of where those stereotypes come from.
Five minutes later that example is gone. It vanished as fast as spam. Why did it happen?
It happened because of The Rule of Cautious Editing Judgment. You stepped on the toes of the vast majority of the wiki, the people who really want to avoid flamewars. This doesn't mean that 99% of the wikians agree or disagree with your opinion on the past President. It just means that 99% do not care for side-issue battles.
Wikis are open to editing from all sides, which makes them self-correcting. For the most part (trolls aside), people want to maintain a peaceful environment. This means that anything that rubs a little too harshly will be wiped away.
While this wiki is built upon being relaxed and carefree, it is still not a forum.
When something is posted that stands firmly on one side of a hot-button debate (political bickering being the huge one, followed closely by religion, with interpretations of Mind Screws running a close third), the editing machine will grind it back down or even kill it outright.
If your example was outright deleted instead of whittled away, maybe there is another method of getting your point across without stepping on anyone's toes. Wording is everything. It goes both ways, too: please do not use the Rule of Cautious Editing Judgement as an excuse to remove a viewpoint that merely goes against your personal beliefs.
The rule applies to examples in fiction as well as Real Life. However, there are some tropes that should not have any Real Life examples at all, no matter how carefully worded. For these particular tropes, the rule is very simple indeed: No Real Life Examples, Please.