Posting copy to arXiv or similar is a norm and not regarded as publishing in another journal.
In some areas like theoretical physics people read mostly arXiv. It does help to shift content control away from publishers.
And they refuse as long as they can. Because they hold the copyrights and universities have no leverage.
The only way to break it is to help their faculty make their journals academic owned. Unfortunately, no official help to record that far... https://twitter.com/Dmitri145/status/1074571804113399808
Just this morning, I've replied to several factually incorrect statements you've made. What can I do to help you get the right information?
"it’s simply unrealistic to imagine that Elsevier, in controlling Mendeley and SSRN, will do anything other than what is best for Elsevier."