I think the only standard we need is that there is a significant body of legible text which is on topic for the forum, meaning about physics or related mathematics, or related methods from other fields, or borrowing from physics into other fields.
If you have an open review, anyone can get a quick review of material, with pointers toward related literature. Any attempt to keep some people out (other than presenting significant legible on-topic original text) will create a political struggle for the keys to the forum, and the result will be that some group of censorious editors will succeed in shutting up a bunch of other people, using political lables.
There is no need for a paper to have any pedigree, in my opinion. Crank papers are the least of our concern, they do no harm, as they are downvoted immediately, and require no special attention afterwards.