... Could the site admins set up a mini tutorial or something for when users sign up?
It's a nice idea, but I doubt it would have much effect. EULAs have trained people to skip past welcome screens and intro pages in order to access the content they signed up for. You can force new users to see a tutorial but you can't force them to actually read it.
At the top of every page is a link to the wiki, which has extensive (perhaps even excessive) guides for users who wish to contribute. Users who are serious about wanting to help already have easy access to all the information they need to get started. No amount of hand-holding is going to help the kind of user who maintains an account for over a year without ever once questioning what the Edit button on each post does.
It's a nice idea, but I doubt it would have much effect. EULAs have trained people to skip past welcome screens and intro pages in order to access the content they signed up for. You can force new users to see a tutorial but you can't force them to actually read it.
Oh no, I don't mean something to read. I mean like a "tutorial" upload, which teaches how to tag, how to edit tags, and how to properly source while also explaining how the site works. Probably wishful thinking, I know, but it might cut down on certain types of posts and comments.