Minimizing core-to-core communication is a nice theory until you actually run workloads with unpredictable access patterns or legacy interfaces bolted on where you can't just flatten and pack everything for optimal cache locality. There's a whole separate world of pain once you start scaling out mutability and pointer-heavy structures: you get play-by-play races between TLB shootdowns, OS-level dirty page tracking and whatever the thread scheduler feels like that day.