The reason is that they want accuracy. If you contend the facts are wrong, prove it.
Net harm from tariffs. Surely if one exists the Cato institute would have it to back up their claims. I believe that the Cato institute claims that India's economic advantage is merely their low wage hard working well educated workforce Maybe I wrong but this site disporves that canard Link
Actually the academic standard if one is presenting something as fact is to reference the source and to allow the reader easy verification of a questionable fact. The presumption being a controversial assertion of fact can then be checked against sources for verification. Now clearly an assertion of fact made before a knowledgeable audience that could be clearly contradicted by the public records does not require such reference. But a "fact" on the actual dollar amount on the investment in China needs an impartial reference. Or are you going to claim the Cato institute is an impartial source of facts. The Cato institute is a clear advocate for open borders and no import duties levied by the USA at least IMHO. if you are alleging this is not the case I will listen to the discussion and I will if necessary back up my assertion with refernces to Cato Institute documents.