That's literally what it's called and has nothing to do with being "inclusive". It refers to someone "outside of the established art scene" and if you study anything related to art, you'll usually encounter it in the form of works created by people in mental asylums: https://en.wikipedia.org/wiki/Outsider_art
E.g. when studying digital archival this was mentioned in the context of digitizing text because there were examples of "outsider poetry" that were written in highly irregular places all over the page and included layers of annotations. That creates interesting problems when trying to serialize and index the text.
In the linked wiki it makes no reference to your claimed origin, 'The term outsider art was coined in 1972 as the title of a book by art critic Roger Cardina' so my point stands, people inside the art world, a closely guarded circuit, decided that the way to define those natural artists who did not have formal training as 'Outsiders', which to me, is not a very pleasant way to describe a people that don't conform to existing paradigms, I don't accept the division, you are of course free to call it what you like.
E.g. when studying digital archival this was mentioned in the context of digitizing text because there were examples of "outsider poetry" that were written in highly irregular places all over the page and included layers of annotations. That creates interesting problems when trying to serialize and index the text.