It takes time to infiltrate, to build trust, to gather evidence, etc. It doesn’t happen overnight and Antifa is a loose group of inbred dumb fucks. I wouldn’t be surprised if the leadership of larger antifa groups like Rose City Antifa aren’t feds or informants.True. RICO was passed in 1970, but you didn't see the massive federal crackdowns on the Italian Mafia start until the late 1980's and it wasn't until the mid-1990's that the majority of the really high-profile cases were all resolved in court. You still had smaller crackdowns from those investigations continue even into the late 90's and 2000's.
Keep in mind that RICO was passed specifically to target the Italian Mafia and the Five Families and Chicago Outfit were fast-tracked for investigation.
I would not be surprised if the Feds are intensely yet subtly investigating Antifa, although if the incident in Portland continues to spark more outrage from normies and centrists, we're probably going to start seeing some indictments and warrants being issued in the near future, especially if Andy Ngo dies from his injuries.
They think they’re clever and smarter than the feds or alt/right and that they’ve effectively hidden their chats and organizing but they’re wrong. If the feds are keeping tabs on a terrorist living in a cave, why wouldn’t they have eyes and ears on wannabe socialists who reject their upper middle class upbringing and live in a first world country using the latest iphones and laptops?