IMHO it’s an exaggeration. Whenever you see just one 5-star rating it’s pretty safe to assume it was rated by creator. It just one star and it’s nothing like you can dupe multiple customers and boast your rating. However, I think that requirement of comment for rating might improve rating situation overall and also fix these “dupes” because I doubt author will publically write boasting comment on their own asset. But really, one rating is not that serious of a problem =/
As for theme topic - demos are nice, they help to understand what you get as a client and also helps to stand out as a creator. I would love if Epic will host it and maybe add a button “Download a demo” and appropriate tag like “Has a demo!”. Don’t like the idea of making it mandatory though.