I linked to the HTML spec because it explains that the slash only means something for void or foreign elements. The <div> element is neither, so the slash is either interpreted as an attribute or ignored. You are correct, both in this comment and the previous one; I was agreeing with you and providing sources.

My comment about the spaces was trivia on top of your trivia. I thought it was relevant because all of your examples of self-closing tags had a space.