It's not self-publishing, it's indie publishing. There's a difference. Self-publishing meant paying for the manufacture of physical books. There was no distribution. Normally the books sat on a pallet in the author's garage. Readers consisted of the author's family and friends.

Small press publishing is a business, just done at a smaller scale than the majors.

Indie publishing uses digital media and distribution networks to put texts into the hands of readers. Hundreds, thousands or tens of thousands of readers may read the author's work. This is indie publishing.