There was arguably a worse period than non-existence, which was when it existed but didn't work very well.
I know of the STL but don't know a damn thing about how to use it. They didn't teach STL at all in my university, even in the C/C++ classes.
We had to write our own Scanner class in our Java classes because the version of Java we were using didn't have that functionality yet. It came out in the middle of the course.
Many video games still don't use the STL due to performance concerns.
They rather use the proper C counterpart, the CTL, written by a game dev. Nobody should ever use set and unordered_map, and many despise string. btree and the various open hashtables are 10x better than the STL parts, (fuck pointer and iter stability), string only recently got improved via string_view.