In a reasonable organization only very minor systems can be undocumented enough to fall through the cracks.
Stuff that’s been working fine for years is easy for a team to forget about, especially when it’s a hidden dependency in some script that’s going to make some process quietly fail.
> Stuff that’s been working fine for years is easy for a team to forget about
That's why serious companies have a documentation system describing their processes, tools and dependencies.
Documentation on every possible system that could use the resource would need to be accurate, complete, have someone locate and actually read it, remember, and communicate it with someone in a relevant meeting which may be taking place multiple levels of management above the reader here. As part of that chain when a new manager shows up and there’s endless seemingly minor details, so even if they actually did encounter that information at some point theirs nothing that particularly calls out as worth remembering at the time.
That’s a lot of individual points of failure which is why I’m saying in the real world even well run companies mess this stuff up.