According to the article, Elsevier demands that the author signs over the copyright. So no, they don't retain complete control.

You are so confidently wrong it's embarrassing.

Any grad student--who does the grunt work in academia--will tell you they would not be allowed to put up their research online without their lab's permission. And grad students sign a form that anything they say and write is owned as IP by university anyways.

Please look into how the academic sausage is made before spouting more misinformation as well as specious takes on spherical-cow free market theories. Your comments are all over this thread and I can't mentally unread them.

Authors have to sign away all their rights when they want to publish with those publishers.