My old boss was an engineering manager at Google in the 90s and early 2000s. He used to tell us that _everyone_ he interacted with at Google _hated_ the monorepo, and that Google’s in-house tooling did not actually produce anything approaching a sane developer experience. He used to laugh so cynically at stories or that big ACM article touting Google’s use of a monorepo (which was a historical unplanned accident based on toppling a poorly planned Perforce repository way back when), because in his mind, his experience with monorepos at Google was exactly why his engineering department (several hundred engineers) in my old company did not use a monorepo.