> You may think peer review is over-rated.

The peer review process is entirely independent from publishers and can (and do!) exist without them.

> not complain about the high cost of peer review

Peer review is not paid for by publishers. It is organized by researchers who are part of editorial boards of journals or of program committees of conferences. And it is done voluntarily by researchers as part of their normal work / duties to their scientific community.

> If we don't need them, why are they still being used?

They are "still being used" mainly by researchers and grant agencies. But this is only a fraction of the number of people who care to read the results of the research work.

Researchers think of their research first, public access second. They think they need to publish with the incumbents to secure their future research. This is because the incumbents own the most respected journal names and have them in tight grip. For most researchers, there is currently no easy alternative way to get credit for their work.

But there are alternatives, it just isn't as easy and convenient for researchers to explore and start using them. The reason most of the people oppose current publishers such as Elsevier is not that researchers do not need them, but it is that society does not need them. It is because business has injected itself in a place where it prevents rather than enables society to benefit from the research.

Peer review is free. The referees do not see a cent of the money paid to publishers.