This is probably one of the issues with being a the aforementioned super-smart / super-productive leader: they can take all of that load if needed. Should they

This is probably one of the issues with being a the aforementioned super-smart / super-productive leader: they can take all of that load if needed. Should they? God no. No one can run that workload as a volunteer for a decade+. But I can see how the default reality probably bends towards "Well, someone left and we need this job filled" -> "I'll just temporarily add that job to my workload" -> "It'd be more effort to move that job's responsibility to someone else, so I'll just keep doing it."