Nobody on the left disputes the fucked up history of the FBI or CIA -- but they're not being dismantled, they're being explicitly weaponized against the Left again. If Trump had said, "The FBI has a racist an unamerican history, we need to shut it down", he might find some common ground, but instead he's pointing at the occasional investigation of someone in his party or social class as evidence of their "wokeness" and firing anyone who dared participate in those investigations while directing them to investigate his political opponents. If you wanted honest FBI reform, you wouldn't let Kash or Dan Bongino within 1,000 yards of the building.
If they are trying to close in on the intelligence and police state because it's not vicious enough against folks they don't like (which includes me and a lot of folks I care about) then a "new and improved" CIA / FBI isn't a "good" thing.
I generally hate the US gov for it's history of doing objectively evil things (I pass by a former "residential school" every time I drive into town), but replacing it with something even more vicious and authoritarian doesn't improve the situation.
This whole neofascist movement is fueled by a mistaken belief that dismantling existing power structures will create a stable situation with more freedom, as opposed to the reality that different power structures will eagerly step into the vacuum.
I think that most of the smarter folks I know on the farther and farther left realize that a lot of what we see are "structural" issues, so voting (for establishment folks) stops being a real strategy at some point. In some sense, that philosophically materialist/idealist seems to be one tool for discerning the ideological differences between liberal capitalists and left anti-capitalists.
By contrast it's not surprising to me that as we go the other direction, the far right is less able to understand that these situations are structurally necessary for the operation of the systems that they support. Convincing those folks that it's not simply who is in charge is likely impossible. It will sound stupid, perhaps, but I have heard convincing arguments that the idea that systems are defined by "who is in charge of them" is fundamentally why "antisemitism" ends up being central to both the conspiracy folks and the fascists.
