1) Old school free speech advocate, changed positions since
2) Had to figure this out practically, so not just theory crafting.
Context: Part of a mod team for a forum, and we were torn between ideals of free speech and what was actually happening on the forum.
Important note, moderation may be the main service the internet/SM platforms sell - curation, removal of trolls, the cleaning and keeping viable an environment for exchange of ideas. Earlier ideas from 2000, web 2.0 etc assumed this would happen naturally. "The better ideas bubble to the top". The market place of ideas.
This metaphor doesn't work when someone is selling goods that destroy the market. If you have a vegetable market, and someone starts selling crack cocaine, then there really isn't something an egg plant vendor can do about getting people to buy the healthier vegetable/argument.
And thats what is happening. On our forum, people were introducing material that short circuits logic. Any long intelligent answer was displaced by an emotional outburst, or cat videos, or jokes, flame wars - on serious topics.
This makes the exchange of ideas moot, and replaces it with the exchange of emotions.
The market place of ideas does not work at the internet scale, even for web forums, unless someone is moderating.
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Additional random thoughts:
First, things are much worse than you feel, because the act of speaking is almost entirely the act of being online. Censorship means you don't get to be heard (although you can speak), so it is, in internet terms, pretty serious.
1) This worked when the network didnt have centralized forces (as value collects in a network, activity increases, and the network will create some version of filters who become gatekeepers.)