For example have you ever been in an argument where you recall reading a paper or statistic, but don't have it on hand? What if that statistic was a false correlation drummed up by a highly politicized thinktank?
This is why it's so important to not leave potentially misleading or outright wrong citations unchallenged. This is sort of how the 'vaccines cause autism' claims can quickly spiral out of control. It requires people to behave earnestly and not mislead with their citations.