Secondly, you're okay with someone inciting violence/vandalism/crimes, and people acting explicitly on that person's direction, as long as only the actual violence/vandalism/crime is punished?
Defamation shouldn't exist (see Alex Jones, that's an insane situation to be told to pay $1.5 BILLION for sharing an opinion) but the standards are generally higher than "someone told lies about my character" at least.
Yes. Everyone has agency, if I tell you to commit a crime it's up to you whether to do so.