There is at least some value in filtering low-quality submissions, wrangling reviewers, and making editorial decisions when reviewers disagree or are just being assholes (e.g. attempting to hinder a competitor).
Yes, but this can all be done without any actual journal, i.e., no physical product, no website (other than the submission link), no typesetting, and most importantly nothing bound by a copyright. This substantially lowers costs. They are called "arXiv overlay journals".
