Relevant lecture from US Army War College: https://www.youtube.com/watch?v=YUpCiA0WZ5k
As someone who seriously considered building a fact-checking website, I am sure that I fit reasonably well into the group of people who would question misinformation, but often I can't find the truth without going through reams of government documents or sifting through tweets.
There have been plenty of things I have questioned, investigated, given up on investigating as unpacking it was a burden, and thought that it was more likely than not that such a thing was true. I have been wrong in that way many times.
The results? No engagement at all.
Cache.
If there are 100 trolls posting: "all birds are blue" you only need to refute it once and link "Are all birds blue? No" article. 5 minutes of damage * 100 vs 30 minutes of undoing
We gave up when we went on Twitter to see just how much nonsense was floating around and realizing that even basic lies took 30 minutes each to refute. Assuming that we had perfect access to people's information feeds and assuming they all believed us anyway (and many wouldn't), we would still need 6x as many people as popular trolls/liars existed to fight back.
You would basically need to have a legion of volunteers willing to spend 30 minutes undoing 5 minutes of damage.