Bone wars electric bugaloo. In the end you really do need a way to discern who is having an appreciable impact in a field in order to know who to fund. I have yet to hear a meaningful metric for that though.

Edit: I should clarify, the other option is strictly political through an academy of sciences and has historical awfulness associated with it as well.

Editors can act as filters, which is required when dealing with an excess of information streaming in. Just like you follow celebrities on social media or you follow pseudo-forums like this one, you get a service of information filtration which increases the concentration of useful knowledge.

In the early days of modern science, the rate of publications was small, make it easier to "digest" entire fields even if there's self-publishing. The number of published papers grows exponentially, as does the number of journals. https://www.researchgate.net/publication/333487946_Over-optimization_of_academic_publishing_metrics_Observing_Goodhart%27s_Law_in_action/figures

Just like with these forums, the need for moderators (editors, reviewers) grows with the number of users who add content.