Tenure-track professors typically have a time limit to prove their worthiness of tenure. At the end of that limit, they apply for tenure and either get accepted or practically fired. One way to prove your value is by publishing in "high-impact" journals. There are all sorts of methods to measure the impact of a journal objectively, such as how often its articles are cited in other articles whose impact scores are also measured. These professors that are in serious debt and have spent their entire lives aiming for this position are practically prisoners trying to get out of the whole they inadvertently dug themselves into. A lot of publications are by those professors, so they are aiming for the highest possible impact scores.

Another group is made up of highly acclaimed professors. They all know each other personally and sit on the editorial boards of those high impact journals. Before they officially submit an article, they send it to their colleague that's on the board or knows someone on the board for review, make revisions, then submit for publication. This likely leads to a bias I like to call "a hook up". These professors practically own the journal, so they have no reason to start a new one.

The rest of the professors (mid-level tenured professors) would be the ones likely to create a new journal that isn't privately owned by a publishing company. Being mid-level and tenured, their only drive to excel is their personal desire to improve the field, so they're not as driven by necessity as the tenure-track or personal drive to excel as the highly acclaimed professors. This, it doesn't really happen because there's no push for it.