Development of anything substantial is an incremental process where parts must exist in an unfinished imperfect state for a time.

Yes, of course. That's why not being able to leave something messy/unfinished/bad is crippling.

I've seen many "perfectionists" hide behind this moniker when infact they're just incompetent when it comes to prioritizing what to do, how much to do it, and in what order.

As you've identified, this thing they're calling perfectionism isn't an asset. I get the sense that you think being a perfectionist is supposed to be a good thing. It's not. It's a defect.