It's been decided by our society that it's illegal to shout the word fire or bomb in a crowded building. It causes unnecessary panic and leads to injury and harm. But the 1st amendment still stands. It is possible for us as a society to reduce harm by restricting the actions that cause harm.
Nothing says "I have no idea what the standard for incitement is" than someone bringing up the 'fire in a crowded theater' cliche from a court case they've never read.
We can get more complex if you want. If I threatened to hunt you down and kill you, in extremely graphic detail, not leaving out a single detail in my writing, I could be at the least detained for it. Harmful speech can and has been regulated in the past. None of our rights are truly unlimited.
The problem is that you're conflating a true threat with what you personally consider 'harmful speech', and deciding that they are also incitements or threats, and the fact of the matter is they're not.
So are we in disagreement then that provably untrue statements sent out to the masses is harmful? Or are we in disagreement that something should be done about it. I'm confused.
I'm saying that people keep bringing up the "fire in a crowded theater" cliche to justify restricting first amendment rights for things that are not actually like shouting fire in a crowded theater.