I agree that sellers should always be forced to be transparent about their previous dealings with buyers. However, stopping users from changing their usernames does not solve this. A seller could simply close and then re-open a new account, leaving all negative reviews behind. The answer Fiverr support gives is that the username is a "unique identifier," which pretty much means the whole website and background systems work off of it. This is not an excuse. It should be quite easy to replace the unique identifier with a number code for each user (only visible to admins), allowing for easy identification of sellers and buyers but with the option to change the username as and when. This is what 99% of companies have been doing for years, like Instagram, to name one.
