Averting threats from abroad is sort of important. E.g. a more capable foreign intelligence organization could have averted 9/11, and with it, an avalanche of changes in the way US citizens live and are governed.
How is that even a question?
More than other intelligence agencies? Extant or historical?
Intelligence is messy. Here. And among our enemies. We have to contain that messiness domestically, to keep it from consuming us. In that way, it's analogous to our immune system. And just like our immune system, turning it off means all the other out-of-line elements around the world now have easy pickings over you.
The CIA has been more destructive than other modern agencies because it's far reaching. It's not more evil than other ICs. Just more capable. I'm not thrilled to learn who occupies that vacuum if the CIA goes away; almost by definition, it won't be anyone benevolent.