During the pandemic, Internet Archive very publicly announced they were relaxing their one physical copy per digitally loaned copy.
I think of they had maintained their 1:1 CDL method, the publishers would still be uncomfortable to be the one to sue first, especially since there was a decent argument and IA would have been pretty sympathetic.
Their pandemic policy was effectively not substantially different from a shadow library., and just set up a slam dunk case for the publishers.