You also have to remember that many people who work in IT departments have gone through years of schooling. Not just at the high school level but college as well. So there is a lot of information that you are asking about. Just look at any college website at the IT selection and you will see there are a wide variety of classes available. IT is a broad subject to be covered. So yeah the IT people know a lot. But they are also specialized in specific areas as well.
So while they maybe great at networking, they may not be great in troubleshooting simple Windows errors and instead restore to flashing an image on a troublesome machine instead of trying to fix the error. As it is less work and a simplistic thing for them to do. It takes all of 5 minutes to deploy an image if done properly compared to the hours you can spend trying to trouble shoot the problem. They need to make sure down time is minimal so they do this to minimize the downtime.
Really this is no different than trying to find what your interested in with computers. There is so much that you can do, you have to find what your interested in and go from there. You can code, troubleshoot, network admin and so much more. Trying to be a jack of all trades is not what companies want. You have to find your interest and go from there.
