by One of the common jokes about mathematics is that you can easily get four mathematicians in the room and none of them knows anything about what the other studies, even though they agree they are all mathematicians.
System administration is rapidly approaching the same point. I have worked with several others in the field who have very little knowledge about the areas that I work in, and I have very little understanding of the areas of focus they have. If you throw in security or network administration, this becomes even more common. But I still see many who argue for a core set of common system administration skills that are far from elementary.
This diversification of skill set is not a bad thing, but a failure to recognize it is. A performance and availability monitoring specialist isn't expected to know the same things as a backup specialist, or a high performance cluster hardware specialist.
No answers here, just something to keep in mind.