I am not so sure. To be a good web developer, you need to have a familiarity beyond css, js, html, and the framework you are using. You should be able to understand the underlying protocol, for example, what do the HTTP headers look like? How are they separated? How can SQL injection be dependent on header contents? You can unknowingly build a vulnerable web app if you don't understand the mechanics.

And in my mind, "serious about programming" extends beyond building web apps.