@frank_d This is a great article, all the information is correct and makes the most sense. I also have experienced the same phenomena that Fiverr title is the main SEO, 90% SEO done there, but nowadays tags and descriptions have very less role on it.
If you see most of the ranked gig on 1st page, they are mostly due to titles and indeed for their performance because if you see tags some of the gigs even don't have keywords in tags that have in their title which shows the validity of this point.