Is this actually helpful? It seems like there are really two options here.
One is that you can have your own database of copyrighted works, let anyone submit one, and the law considers that sufficient. But then everyone has their own database that starts with nothing in it, none of them really ever have more than 1% of the total copyrighted works in them nor ever really catch anything, and uploading everything to everyone's database is completely intractable so nobody bothers.
The other is that having an incomplete database is insufficient, but having a complete database is still intractable because anyone else can at any time create a new copyrighted work that isn't in it. And then troll you with it because they know it isn't in any database but can have someone upload it to your site just so they can use the law to destroy you. No database will ever contain more than 1% of the total copyrighted works, because they're created by the millions every minute of every day.
So does pooling together like that actually buy you something? It doesn't seem to change the "are you screwed" calculus much one way or the other.