No, that’s not what they are saying. They just listed the 12 worst. That doesn’t mean there aren’t more disinformation artists, it just means they noted the 12 most prolific.
If they bothered to list the dirty 2 dozen then the other names might be there.
I saw a demonstration of what I believe to be camoflauged DARPA software used to cull the web, track down sources of influence adn target them. There was no ‘top 12’. It was strictly identify and silence objectives. The wording of this software demonstration was warped and fake positive - I recall the Dems used DARPA software in the 2020 election which they designed to destabilize Iran. I think that’s likely part of the software ‘suite’ I saw demonstrated. So I agree with your point that there’s more than 12.