I see #13 (human expertise) crop up the most often in the complex systems at my work. I think the two main reasons replacing experts is so hard is (1) it's inhe

I see #13 (human expertise) crop up the most often in the complex systems at my work. I think the two main reasons replacing experts is so hard is (1) it's inherently difficult to understand another's work you haven't built from yourself and (2) it's nearly impossible to find someone as enthusiastic for taking on a system and giving it the TLC it needs to keep it going smoothly to the extent that it matches the passion that the original creator poured into it. I find this most acutely whenever the original expert refers to it as "their baby".