I dont think they replace each other, they are complementary - they do overlap though, which is why people think you can trade them off - a test is not creative, a human is not an automaton.
We have been using humans for automations for a long time, factories have been a thing for quite a while now.
They have an intersection, the fact is that you might need only the benefits in the intersection, not all the benefits. Given that, it could make sense.
I have way more fun writing tests, but automating certain things have a steep maintenence cost, a checklist for humans is a better idea in that case
