Is this a summary of the book? Why don’t you list arguments or chapter outlines?

No — the focus is on thinking shifts, not content coverage. Unsans is concerned with effects on thinking, not internal structure and deliberately avoids summarizing content or chapters. It focuses solely on the central thematic idea of the book, and in that sense, it is not a summary or a gist of the book. Think of a book’s entry on Unsans as a document of after-the-fact impact: the intellectual shift occurring after the reader finishes the book.