Nowadays, Google's having trouble hiring enough people with sufficient web skills. And the reason is because the web basically "grew up". In addition to HTML, you also need to know CSS, JavaScript, how to write maintainable JavaScript, DOM APIs, browser quirks, performance tricks, emerging web standards, and at least one server-side programming language. The definition of a "web developer" has shifted so that it's really a full-fledged programmer with specific domain knowledge, akin to the skill level needed to do compilers or embedded systems. And the barriers to entry have become correspondingly bigger; you don't see as many high school kids writing major websites any more.