@jonny: Agree 100%. It's wild because the original Frontiers was a solution to the prestige treadmill system. (@neuralreckoning : I think the original Frontiers systems identified below are both wonderful ideas we should try to get back. (ideas for your new list))
When Frontiers started, it had a host of important changes that were really good. Then it got bought up by the prestige publishers and they are basically all gone now.
A new peer review process that provided gatekeeping without prevention. The peer reviewers "endorsed" a publication. You could reject a publication, which said "I refuse to put my name on this", provided (private) feedback to the authors and your name never appeared. (Authors never saw that reviewer's name either.) But another person could endorse the paper.
What this meant was that you could tell the quality of a paper by who was willing to endorse it. You could use that endorsement to judge whether you wanted to trust the paper.
In practice, papers got rejected when none of the reviewers in the field were willing to endorse the paper. So papers could get effectively rejected when the field didn't approve of it (no one would endorse it), but no one person could gate-keep a paper.
Papers moved UP not DOWN.
The first publication was in a field specific journal (that was generally low impact) and was judged on scientific merit, not impactfulness. Then, based on actual metrics (like downloads, votes, etc), the authors would be invited to write an article for a second-tier journal (less field specific, more general). There was supposed to be third-tier journals, but I don't think they ever appeared. When Nature bought Frontiers, I tried to convince the editors at Nature to create one slot for a paper in Nature so that it could serve as a fourth-tier journal, but they weren't having any of it.
In those early days, we had a lot of success with those two-tier Frontiers systems.
jonny