Re: no systemd here
IOW, gestalt faults (or gestfaults, for short). Things that never show up individually but crop up when put together (the whole is worse than the sum of its parts). And that's another potential fault point for a process chain: "trusting the welds", so to speak, since you can't be sure the two programs were built by the same teams with the same goals and same philosophies and expectations. If they don't, and they don't explain everything, an edge case can hit where the sender sends something the receiver doesn't expect.