The idea is that you absolutely should not have hierarchies and other systems that put individuals into power, as those will inevitably be usurped by bad faith actors, or even more likely, corrupt those granted the power.

And how is this state of being enforced? Narcissists will not just obey the rules because people said so. They will create hierarchies without anyone's consent, and they have a wide variety of methods available to them for doing so when presented with a naive population (which I still maintain that leftists largely are, at this point).

Even if you somehow maintain a non-hierarchical state, but do not remove the narcissists, you will still end up having to deal with the social and psychological damage that narcissists do to everyone around them regardless of whether or not they have any kind of special power over others. Why would you want to tolerate this?

What you propose will just result in a witch-hunt with a lot of collateral damage

Only if you mis-identify the bad actors. Part of educating people about how to reliably identify these people is also teaching them how to not mis-identify someone who is not one of these people.

power corrupts even those that are not narcissists to begin with

This premise is actually just false. The psychology and anthropology makes it plainly clear that power does not corrupt - it merely reveals who a person really was all along. If you actually understood narcissism, you'd understand how they mask their personality so that people don't realize just how self-centered and abusive they are. When you give narcissists the ability to avoid accountability (something that typically comes with power), they loosen or even take off the mask because they no longer need it to protect their status, and it is a lot of effort for them to maintain.