https://www.nature.com/authors/policies/license.html
Standard practice in the modern AI community is preprint to arXiv first, then out to a journal for review. All the papers are free online before they even go to Nature. So this policy does not stifle or hinder research.
They also do not take copyright - it stays with the authors - unlike other giants such as IEEE.
To my mind the legitimate argument is about publishers taking undeserved profits from unpaid labour while adding little value.
(edit: reordered sentences)