The grid fails catastrophically. It happened this year in Portugal, spain and nearby countries? Still, think of the grid as more like DNS. It is immense, but the concept is simple and well understood. You can quickly identify where the fault is (even if not the actual root cause), and can also quickly address it (even if bringing it back up in sync takes time and is not trivial). Current cloud infra is different in that each implementation is unique, services are unique, knowledge is not universal. There are no books about AWS's infra fundamentals or how to manage AWS's cloud.