> Belief in free speech as a principle assumes that good and right arguments will win out every day in an open public forum

That may have been correct 50 years ago, but technological changes since then call it into question.

It used to take a fair bit of effort on the part of information purveyors to get their information out to a wide audience. Generally you couldn't just come up with a bad or wrong argument and get it rapidly spread far and wide.

On the receiving end, it took a fair bit of time or effort to access information. We might regularly watch a scheduled TV news broadcast, read a daily newspaper, maybe also read a weekly news magazine to get a broader or deeper perspective, and also maybe read more specialized magazines for news and information on more specialized topics we were interested in. If we needed to go beyond that on a particular topic, we'd have to go to libraries or bookstores.

This combination of bottlenecks on both the production and consumption end meant that generally by the time bad and wrong arguments could start to get traction past a fringe audience there would have been time to develop good and right arguments to counter them, and that people would see those good and right arguments.

Nowadays, the barriers to widespread dissemination of the bad and wrong arguments are way lower. On the receiving end, instead of getting our information by setting aside time each day to read/watch a small number of high quality, consistent sources, many people get their news as a side effect of social activity. It is much less likely now that when they get a link to that bad and wrong stuff that they will also get a link to the good and right refutation. And remember, because the dissemination barriers are much lower now, they are getting the bad and wrong stuff on multiple topics, so even if someone does send them a refutation on one they might be too busy looking at the sensational bad and wrong stuff from another topic to go back and read the refutation of yesterday's stuff.

I think that most people recognize that it is important to be well informed. 50 years ago it took some work to be well informed, so we had to put some thought and effort into becoming so. Now, it is easy to think that you are getting well informed as a side effect of your other activities.

We weren't smarter back then, or less gullible, but there simply was much less of a grey area between uninformed and informed. Now there is a big grey area and it is easy to end up in it. The "let the good and right win out in open public forums" only works if the people in that forum who think they are informed actually are. If they are in that grey area, all bets are off.

The situation 50 years ago did have some problems, mainly that sometimes a thing that is actually good and right appears initially to be bad and wrong, and those barriers that helped keep bad and wrong things from spreading would also slow down those "really good and right but looks bad and wrong" things, too, so it took longer sometimes to adopt new good things.

We've removed that friction...but we've removed too much of it. You need some friction to slow down a bit so that people have time to evaluate and react.