The scope tag is for questions about the scope of the site. That includes questions about what kind of things are on-topic or off-topic, but there have already been four questions using the on-topic tag, three of them without using the scope tag.
Please can on-topic and off-topic be merged and synonymised with scope?
I know I could just retag those questions manually, but a synonymisation would enable people to choose the right tag when typing topic
into the tag box on meta.