That was my understanding. Maybe something has changed?
eg. I am not a member of the “theme author” group. When I go to the category I see a “+ new topic” button that does not function.
theme - Discourse Meta
I know why because I have read
About the theme category
If you have developed a theme you would like to share, PM
@samand ask to be allowed to be added to the@theme_authorsgroup so you can post your theme.
I don’t have much faith that members actually read what’s important to read, so IMHO it would be better to not show a non-functioning button. Better yet might be to have the button and show some kind of “you need to ask to join” modal.