The goal with automation is that the number of unidentified corner cases reduces over time.
A manual runbook is a game of, "I did step 12, I think I did step 13, so the next step is 14." that plays out every single time you do server work. The thing with the human brain is that when you interrupt a task you've done a million times in the middle, most people can't reliably discern between this iteration and false memories from the last time they did it.
So unless there are interlocks that prevent skipping a step, it's a gamble every single time. And the effort involved in creating interlocks is a large fraction of the cost of automating.
A manual runbook is a game of, "I did step 12, I think I did step 13, so the next step is 14." that plays out every single time you do server work. The thing with the human brain is that when you interrupt a task you've done a million times in the middle, most people can't reliably discern between this iteration and false memories from the last time they did it.
So unless there are interlocks that prevent skipping a step, it's a gamble every single time. And the effort involved in creating interlocks is a large fraction of the cost of automating.