Earlier quoted context omitted.
Not sure if you're asking about the role that academic journals play in general, or about what specific actions publishers do. Journals in general serve to curate an ever-increasing body of research and provide a crude method of gauging scientific quality, relevance to your field, and importance. They provide a crude method of judging the impact of scholars without having to read every single paper ever published. Pu…
The only tangible benefit I can read into that is peer review, which isn’t paid for by the journals at all. Open access journals have demonstrated the ability to have effective peer review journals without the middlemen. Otherwise you haven’t mentioned anything of actual value.
Open access journals are basically the same as traditional journals, they just charge authors up front, rather than readers later. I don’t understand what you mean by your sentence above - they haven’t demonstrated anything close to what you claim.