I completely agree (and said in my post) that any single anecdote can come with all sorts of problems.
I just believe there are too many people repeating such criticism thinking it'll make them sound smart, when in reality, they wouldn't be able to function if they didn't trust single data points almost all of the time.
Most of these occasions don't appear to be "trials" to us, but they actually are. Examples:
- "I really enjoyed that restaurant and will go back there soon"
- "Don't take a taxi from the airport! The train is much cheaper and the taxi driver just ripped me off"
- "The Hitchhikers' Guide is a great book–I should read another one by Douglas Adams".
-...
All these are essentially statistical trials with n=1. What makes single experiences in these cases possibly relevant is (among other things) our believe in the low variability of what we're measuring: A restaurant's quality doesn't usually change dramatically from one day to the next etc...
Then, there are more complex examples, where learning from n=1 is slightly more dubious, but without alternatives: "Don't start a land war in Eurasia", or the other German saying: "It happened, therefore it can happen again". On a more personal level, we all have to learn an awful lot about human relationships from a very limited set of experiences.