That seems more plausible to me than the CIA directly and solely being responsible for killing JFK tbh

You have to understand, when a lot of deep politics people talk about this stuff, when they say the "CIA" did something, they don't necessarily mean the literal organization. Factions of the intelligence services or the military have people trained in covert action who are capable of fulfilling multiple roles at once, and those people can have connections to other factions of the bourgeoisie or organized crime. In this sense, the CIA is not so much simply an intelligence agency, but a nexus for an organized crime network that operates in the service of the (primarily American) bourgeoisie.

This network is especially good at messing with the internal politics of countries in various ways, in order to manufacture an outcome that best serves the interests of capital.

They’re bureaucratic and patriot-brained enough to “respect” domestic institutions

No, they absolutely are not. We know what these people were like in the 60s at least, and they were utter psychos.