That's generally true, but there's a more specific affliction you sometimes run into that the parent comment is referring to.

There are some single software programs so big and complex that you can build entire careers out of them. People who do that become wizards within that software suite, and then incorrectly generalize that to believing they know everything about computers. When really, they are Photoshop jockeys, Avid editors, Maya artists, etc. and they are mostly lost outside of those applications.

If you haven't worked in creative fields like video you may not have run into them, but they are definitely a breed.

(Developers fall prey to this sometimes too, but our job tends to require us to use a variety of tools and the underlying operating system itself, so we do end up with a greater breadth of experience.)