It seems we have two behaviors and purposes for the Writing section in Site Settings with the default post category and format options.
One behavior allows the user to update a site's default post category and default post format, while the other allows the user to update these settings locally for use when posting via the editor. However, this changes a bit when the settings cannot be synced to/from the site.
XML-RPC: As seen in #4749 the default category and default post format site settings are not pulled or updated to a blog via XML-RPC, but are available within the app.
REST: The settings are available and synced for admin users both to the site and within the app.
REST: The settings are not available for non-admin users to sync to a site and cannot be used within the app.
It seems we have two behaviors and purposes for the Writing section in Site Settings with the default post category and format options.
One behavior allows the user to update a site's default post category and default post format, while the other allows the user to update these settings locally for use when posting via the editor. However, this changes a bit when the settings cannot be synced to/from the site.
XML-RPC: As seen in #4749 the default category and default post format site settings are not pulled or updated to a blog via XML-RPC, but are available within the app.
REST: The settings are available and synced for admin users both to the site and within the app.
REST: The settings are not available for non-admin users to sync to a site and cannot be used within the app.