Teaching yourself a concept, especially doing it by creating, is one of the best ways to learn something. It's usually fueled by passion, which you can't fake.
It also can leave knowledge gaps that are hard to identify, that you wouldn't have from a traditional educational background. On the whole, I personally feel like I know better the tools and technologies that I taught myself, though I definitely appreciate formal education in other areas.
Even something as complex as Photoshop, guidance has been appreciated. Programming? Love the structure! Specific programming languages and tools? Generally prefer self-taught.
If others learn the same as I do, I question the value of a formal education or certificate compared to being able to walk the walk.