8 years later, I learned something. Solid. Very solid. Thank you for sharing the knowledge, Dan!
8 years however is an eternity in the world of SEO. Are there any updates on your stance re. this problem in particular?
Following your guide and generating reports to put them in the "Nay"-bag, I want to delete them. I'm going to remove them from index first by nofollowing the tags taxonomy, and removing from XML sitemap.
So, the big "What if" ... What if I simply delete all of them after doing so?