That's a common misunderstanding.
Kiddie porn, well yeah because it violates the rights of a child that had no real choice.
Any other kind of porn? Obscenities? Nope. Government doesn't restrict that. Only the FCC restricts free public / unencrypted broadcast.
What regulations are there against "fighting words?" You're allowed to say them, and in some cases a threatened person could be justified in attacking you. Fighting words are not forbidden.
False advertising is simple theft by deception. That's not restricting free speech at all. If a false advertisement didn't cause you to lose money or time, or cause you any other kind of loss, you probably can't do anything about it.
What about if your free speech is about how all Jews are masterminds bent on global enslavement, and all blacks are violent criminal thugs, and all Muslims are radical terrorists devoted to forcing Christians under Sharia law? And this speech spreads so that people in those groups are murdered and/or subjugated?
Is that speech still just 'ideas' that doesn't cause any harm?
One of the great failures in this alt-right philosophy is that freedom should exist without moral constraint or ethical responsibility. It's why that movement embraces trolls who do nothing but tell lies for fun, like the OP. Or imagines that their free speech is so important that there should there be no reasonable societal constraints upon their speech, that their speech is somehow infringed when others speak back to disagree, or choose to voluntarily disassociate themselves.
The reason we're having this discussion is because no right can long exist when its abuse is tolerated. IOW, there would be none of this speech of curtailing free speech if people weren't being irresponsible with their right to free speech. Alt-right trolls continue to insist this about speech others disagree with, but disagreement has nothing to do with another shot up synagogue or mosque. It's about a failure to act responsibly.
I will now wait for some douchebag to call this virtue signaling or some BS like that.