I think the argument the poster is making is as root cause analysis.
The root cause of the messenger failing was the missing nail. Sure it could have been many other things, but in this case it was the nail. And if it was a pitched battle that was narrowly lost by one message, sure, they could have won or lost because of a dozen other factors, but in this case it was the missing message. There are likely many other important things to worry about, but in the system as it is today, it failed for want of a nail.
Plenty of large engineering outages were because of single keystroke typos. Should these systems be less prone to human error? Of course. Are they? Some of them are, but right now some of them aren't.
The point being made is that small things can be important if other things go wrong. We should fix the other things, but often they are much harder to fix than the small thing. And really, we should care about both, since humans are capable of that.
For me, this is the moral of horseshoe nail story. It's something I preach to my team - details matter. I’ll add that unfortunately we often don’t know which details will matter ahead of time.
If you look at the problem as a swiss cheese model and not just a teleological propagation from one root cause, then there are many things that need fixing, not just a cobbler being short one nail.
The root cause of the messenger failing was the missing nail. Sure it could have been many other things, but in this case it was the nail. And if it was a pitched battle that was narrowly lost by one message, sure, they could have won or lost because of a dozen other factors, but in this case it was the missing message. There are likely many other important things to worry about, but in the system as it is today, it failed for want of a nail.
Plenty of large engineering outages were because of single keystroke typos. Should these systems be less prone to human error? Of course. Are they? Some of them are, but right now some of them aren't.
The point being made is that small things can be important if other things go wrong. We should fix the other things, but often they are much harder to fix than the small thing. And really, we should care about both, since humans are capable of that.