If you learn cybersecurity you will be hired by companies who want to either test their security or have you implement one. How are you supposed to know how to do that if you don’t know how a website works in the first place. How to work with a website. If you could tell the it guy to just „do xyz“ there would be no reason for them to hire you.

Someone being a Webdesigner has to know how a website works too to be able to design one. They can ignore security and resources for the most part, but they have to know how to make their pretty website run in the first place. Otherwise you could just hire a graphic designer to make a few fancy drawings of their website and hire someone else to build it