The important thing to keep in mind is that this is true in a context where good statistical evidence is available. Rationalist advice tends to degrade over time to its literal meaning. In light of the title it is important to emphasise that someone providing contrary anecdotal evidence against your own or someone else's anecdotal evidence, obviously shouldn't be down voted.

In the absence of strong evidence, especially in new or uncommon areas, anecdotes may be the best thing you can get.