No matter what you are doing in life, no matter which job you make a living off, you will have to “own your art.” A photographer needs to know image composition, a writer needs to be able to throw together captivating headlines (“Attention WordPress developers: Are your clients trying to kill you?”), and a chef has to be able to make more than mac ‘n’ cheese from the box.
As a developer, owning your art comes down to picking your favorite acronym: HTML, CSS, PHP, JS, maybe some MySQL. Which language you emphasize depends on what you are doing, however, your technical skills build the foundation of everything you do. They are the price of admission. Make sure you know your stuff and that you continuously hone your skills.