It is possible to move that complexity into the platform and outside the applications themselves. When I build a web application I don't need to do anything special about failovers, as long as I remember the local filesystem and state is fungible and it only is persisted when I persist it someplace else (that also employs the same safeguards).

I liked to use Google's App Engine classic environment (the Python 2.7 one) as a good example. It really hammered down some good practices (such as keeping the filesystem read-only) and gracefully handling degraded modes such as a datastore that becomes read-only for no reason or the cache that's supposed to be there that just isn't. It was a great teaching tool.