That is not universally true. Under US law, incitement is a crime if it pertains to imminent action. If it's an abstract discussion about the future, then it falls under free speech law, which is not a crime.

I do acknowledge and understand that this particular case did involve imminent action, and it was in Poland. Even so, it is wrong to generalize a law. For those in the US, it is an insult to the First Amendment to generalize it.