Stilly River Sage wrote: ...on the Mudcat Facebook page (that's an ideal spot for that kind of post because we've kept the page public so anyone can see it and share the posts.

As a non-member to FB I can scroll down a few posts, before it covers the screen with a banner saying:

There's more to see.
Log in or create an account.

Some 'public' groups put the 'Sign in or sign up!' banner up sooner than others; I don't know why they vary. 'ABC Notation' is particularly restricted.