The STL is a product developed and maintained by SGI. If you look at the containers listed in the article and on the SGI page, you will see a different set than is present in the C++ standard library, especially if you discount the containers that weren't in the C++ standard library when the article was written.

Now, people often refer to the C++ standard library as the STL, but the author of the article was clearly confusing the STL itself with the standard library, not just the name.