Both the Splendor and Liberty engine room fires left the ships nearly powerless. I know next to nothing about ship engine rooms or power systems so my comments/questions are purely out of ignorance.
I have always assumed that modern cruise ships would have port and starboard engine rooms separated by a firewall each with separate fire suppression systems. I know with even the most redundant systems there must be a cross over point that can be a single point of failure. Nevertheless, you would think the remaining engine would be sufficient to provide basic hotel services.