You know why I created [citation needed] on Wikipedia? Because the amount of ill-informed, badly thought out, ridiculous claims on Wikipedia articles were getting out hand. I started removing them to the talk page, but then that same person not only refused to explain where they got their information from, but would put the "fact" back into the article. This would then perpetuate incorrect information.

One day I had an epiphany. I realised that you can't just argue with these people, you need to have a reverse citation system - you need to clearly mark out information that is dubious, ill-informed, the result of ingrained prejudice (often unconsciously so) and almost always inaccurate.

At the same time, there needed to be a way of allowing controversial views and sometimes accurate but controversial facts be detailed on the encyclopaedia.

There was only one way I could see to do it - use the same citation system that referenced sources but invert it to highlight information that needed a source. Hence I created citation needed (originally without the square brackets, whoever added them was a genius in their own right).

Guess what? It worked. 11 years later, despite the many issues on Wikipedia, finding out the source of assumptions is no longer a problem. People can go to the citations and see where the factoid is documented, or whose opinion is being expressed. It allows ordinary people to judge the view being expressed more accurately, or to look at how the data was extrapolated, to understand how the academic study was conducted, or to verify that what is claimed is actually what the original claimant was indeed claiming.

On Wikipedia, there was no way of allowing people to say that you are full of shit without destroying the project. Yet people needed a mechanism to dispute what was written. Talk pages weren't enough - bad actors could keep conversations going indefinitely without really bring challenged, whilst most readers wouldn't see the controversy of their contributions. By marking up text with [citation needed] it allowed people to think "hang on, this is disputed, where did they get this idea/information from?".

If my one contribution to society all those years ago was to have helped people improve their critical faculties and question the information given to them, then I'm satisfied I've made a positive impact on society. I certainly didn't expect it to take off like it did. I'm also not arrogant enough to think I started this questioning, merely helped start a meme that was actually useful.

If Hacker News now has its own culture of asking "where did you get that information from?" then it's a [citation needed]. You should applaud it. You should cherish that people have found a way of politely questioning the views of others and make them justify what they say without resort to personal abuse. You should be happy that people are using their critical faculties when they question implicit assumptions and claims.

You say it casts doubts on the truthfulness or provenance of the original poster's claims. Good! If the claims are of good provenance, then the poster can show that provenance. If the original poster is being truthful, then they can prove it by showing their sources.