Every person is “useless” when things go well or everyone else can fill in (which is most of the time). The point of a manager is handling the snags and keeping it out of others’ hair so they can focus on their tasks.
You only appreciate it when you actually know what good management looks like. It sucks how rare it is, though, I’ll give you that. About as rare as having parents that know how to parent and instruct without the authoritative cliches. (or hopefully that situation has improved by now but I dunno…)