It'd be great if this could one day be a real alternative to Elsevier. Today, professors and postdocs are doing the peer-review for Elsevier, for free. They can do that because they get a paycheck from the government (through university and grants). Then, the governments pay for Elsevier access through university libraries, ontop of that. It'd be much more efficient, if everybody could just publish and subscribe for free on a publicly funded platform.
You absolutely need to solve the gatekeeping and reputation part, otherwise your newly-minted open access journal would be filled to the brim with cranks and charlatans.
There are many more publishers than Elsevier for scientific publications, some of which are already following a strictly open access policy.
Arxiv and the internet do more for science than Elsevier. They're rent-seeking middlemen, having lost any of whatever their purpose might once have been.
I think the worst part is, Elsevier could still serve a purpose and make money by curating and leveraging reputation even if all academic research was openly published and freely accessible - they could select what they consider to be the best research, have editorial content, produce visualizations and accompany content with a high quality of journalism, like Quanta. Papers being locked, researchers and institutions paying out the nose, and the other artificial scarcity / artificial stupidity features are entirely unnecessary.