This sort of litigation is not about who’s most at fault - it’s about who can most efficiently be made to pay.
The claimants (and more importantly probably their entrepreneurial lawyers) want to run a single class action against a deep-pocketed defendant with a lot to lose.
They don’t want to be running a bunch of cases on behalf of a bunch of individual clients against individual creators who have no readily available assets, may not be in the US and have no corporate value to protect.