Well, that is true when there are several languages that overlap (for example, you might want to do some server stuff and you find that there is C++, Java, C#, etc.); however, if you are trying to learn the web, then you definitely need to learn HTML and CSS, since those are the only languages available that do the thing they are good at.
If you are trying to build websites, then that's the way to go.
If you are trying to build websites, then that's the way to go.