While that is one way to look at it, it is also true that more people are exposed true information as well, many people have been brought OUT of these toxic groups due to exposure to more information online
You are only looking at 1/2 of the equation. On Balance I think it is a net gain for side a truth.
Keep in mind that media and human in general tend to be bad at risk assessment, People believe they have a greater chance of dying in an airplane than on the road as an example, or that terrorism is a greater threat than it is. Or more recently slight up tick in violent crime is worse than it really is...
Sure some people that may not have been exposed to things like the Flat Earth or Anti-Vax were, but I did to look at the over sensationalized media reports of these groups being "epidemic" that social media is to blame for as self serving since the media is used to being gate keepers of information, having lost that power to social media and the internet in general they are looking to demonize the technology in order to regain their position as the Arbiters of Truth
Dont get me wrong, I think Twitter and Facebook are terrible, I just to no support the idea that solution to these problems is with centralized "Fact Checkers" who are conveniently part of the old guard media establishment,
Make no mistake that is what ars is pushing for.