Message-passing is popular in HPC (e.g. MPI) because it more closely models how hardware works. But at a higher level people mostly prefer to build abstractions on top of it like async/await because message-passing requires you to manually compile your flows into per-process state machines, and that's not how most people think about flows (even though business people do sometimes: https://link.springer.com/chapter/10.1007/978-3-540-72863-4_...).