I feel as though there should be a standard set of tests that any or all fonts run through to demonstrate the various properties they want to claim. Don't tell me "better", tell me "Scored an 8.6 on legibility in the standard font assessment test".
Why do content creators need to do this? Particularly if they are experts and live off the trust in their experience. I am very happy if someone publishes something and states there goals an claims, so someone else can verify them independently. If it is not working they would risk reputation.
If a few publisher's really check accessibility against relevant end users and verify that this works it is much better, than any kind of scores that often overlook important usability/accessibility issues.
a11y Checkers are OK like any linter but I think we should not overdo this. That something has a higher score does not translate to better overall a11y.