They are ostensibly appable. We only meet two of them, and only one face-to-face (Ish. They don't really have faces.), but they're a species that is specifically designed to take power and freedom from people and they are anti-progress, so actually apping one would be awkward. In canon, they have tendrils they can stick in your skull allowing them to literally control you like a puppet if you're close enough and have advanced this skill to be able to achieve the same effect by way of the cybernetic implants just about everyone has to access the future-internet.

They could be replaced by some other kind of threat that controls people, yes. Did you have someone in mind?