I haven't found the opportunity to block itch.io users from joining game jam. As you might not know - there are some people that post their games on every game jam on submission in order to promote their game. Everyone has to manually delete them every time and it's not actually a problem if you know which games have been made during the jam and which are fake, but it would be a nice feature and it would make a jam hosting easier. Also, you might miss the game and it could actually influence other games rating.
Can there be a feature to add those people to user black list, so that they cannot participate in any jam that was created by that user?
Also, make some sort of searching inside community topics, either there is one, but I haven't noticed it or there isn't and it must be implemented. How would I know that the similar topic has already been created, so I won't do a duplicate?