Regarding the "wallpapers" community... I get why they have the rules they do... but the rules aren't very conducive to sharing wallpapers like we normally would. Looks like it's trying to get all OC posts, rather than sharing neat ones we find across the web.
For context as of today (June 13th) they have "You must own or have the right to share any wallpapers you post. Include the source in a comment. Posts without a source will be deleted. Copyright violations will result in a ban." as a rule.