In general I think I agree with you, but on forums this is subtly different.
In a general internet forum, it's up to you decide what you read. On FB, there's an algorithm that determines your feed, and therefore the profit of Facebook itself.
If FB were connecting people, making the world a better place, and making profit by doing that, I think I'd be fine with that.
But it looks like FB can trade the general good will of people, replace it with extremism and make a profit doing so. And if that's true, I think we need to seriously look at section 230.
There's a series of commons that we all share (e.g. water, air). I'm not quite sure if this fits in this category, but for democracy to work, people have to agree to not resort to violence to solve their problems. Trading the common good will for your fellow country men for profit, while watching the world burn, is I think not what we want as a society.