In the limit, there is a hard tradeoff between efficiency and reliability.

Failovers, redundancies, and backups are all important for building systems that are resilient in the face of problems, for reasons you've pointed out.

However, failovers, redundancies and backups are inefficient. Solving a problem with 1 thing is always going to be more efficient that solving the same problem with 10 things.

It's interesting to see this tradeoff play out in real-life. We see people coalescing around one or two services because that's the most efficient path, and then we see them diversifying across multiple services once bad things happen to the centralised services.