... because both jobs are damn hard!

I think the "programmers can't be sysads" folklore comes from two beliefs: (1) sysads and programmers were adversaries back in the days when programmers fed stacks of cards to the Machine God behind the glass window, and (2) programmers are theorists with no concern for the real world, while sysads Get Jobs Done.

In truth, the same basic skills apply to both jobs. Sysads need to handle pressure a bit better. Programmers need to handle abstraction a bit better. Sysads tend to use lousy tools too, so secondary skills like record keeping are more important for sysads.

The biggest problem both jobs have is the folklore that people can learn them by taking some ad hoc training. Many people without formal training have become good sysads and programmers. The big lie is that people don't need structured, progressive, disciplined training. They do. If someone doesn't have the self discipline to do that independently, he or she really needs the support of a university. (or monastery ;)