I don't think direct incitement to violence is useful, and most legal scholars don't consider it protected under the 1st amendment.
There are a lot of other kinds of speech that most free speech advocates recognize as not helpful and potentially illegal such as fraud, disclosing secrets when under an NDA, perverting the course of justice (although that is debated, e.g. Tommy Robinson), disclosing troop movements during wartime, etc.
> and most legal scholars don't consider it protected under the 1st amendment.
While I don't think incitement of illegal violence should be legal, I think whether scholars think that something is legal, under the status quo of some country, is a terrible metric for whether it ought to be legal, and the standards it should have.
Laws must be followed, but can be wrong and can be opposed.