tl;dr: The author argues that "simple" (decoupled) is often conflated with "small," using Unix pipelines as an example: they're small but tightly couple concerns like aggregation and ordering, making modifications painful. In contrast, large programs like Google Drive or Clojure's map-based structs can be decoupled and thus simpler to use and extend. Writing truly simple software is hard and sometimes requires massive engineering investment (see SQLite, Blink), but coupling should always be minimized regardless of program size.