You are 100% right about that. But think about it like this... if you learned intergrals first, would have have bothered to learn to calculate the area under a function using a series? Probably not. Sure, there are things you can do with a series that you can't do with an integral, but the integral is so much easier, you will never learn how to use a series.
Systems administration (as well as progamming, heck, anything!) tends to be an 80/20 proposition. If you don't maximize your learning up front in the initial learning period, chances are, for most people, they will almost never go beyond what they know.
I have met way too many people who thought that they would ease themselves in Linux with a GUI, and learn CLI later, who are still basically Windows users on a different platform, to beleive that people can do this. Sure, there may be the occassional person who has the motivation to ease their way into it. But I just have not met this person, including myself.
I didn't truly learn UNIX (always had to use X, and know the basics of CLI for ages) until a Windows server died, I had 3 days to replace it, and I didn't have the cash to buy a Windows Server liscense (the liscensing was a long story, in a nutshell, the Windows liscense was a bit "grey" and I wanted to be fully legit). When someone has a contractual gun to your head, you learn, it's that simple.
Again, yes, it can be done like that. But most people will not. The GUI is friendly, it is comfortable. It's like if you lived at home and your parents fed you and bought you cars and paid the bills and bought you beer, would you bother finding a job?
J.Ja