This is more like owner of a noticeboard being liable of things posted there.
Either have a human verify everything nailed (the upload filter) or just remove the noticeboard. Which one will happen?
Libaries and bookstores are more comparable to online shops. I have no qualms for Steam being liable for selling a pirated game. Shops should have verification on products being sold.
I just don't understand why OSPs get a free pass while brick and mortar content curators have to obey the law while struggling to pay the bills.