I think the problem in this line of reasoning is that it implies that the central problem with Trump's presidency was his incompetence; he was inexperienced as a politician, ignorant of appropriate procedure and protocol, so that's why his administration was a dumpster fire.
Not saying he wasn't ignorant and incompetent, because he was and is, but unfortunately those are not his worst features. I think you could get, say -- a car mechanic, a musician, maybe a teacher -- who is also emotionally stable and is capable of basic compassion and empathy, and somehow elect them into the role of president, and despite their not having any experience or really being cut out for politics at all, I'd predict their administration would be less damaging than this one.
Plus, W's administration was a dumpster fire too, and he'd been a governor. Nah, the problem is not that he hadn't been in public office. It's that he's a terrible human being.