If you're going to program any modern game, you're going to need to use plenty of libraries / operating system capabilities beyond the C standard. Threading would just be one more drop in the bucket.
That said, to the original poster, games are much less multithreaded than you think; threading actually slows things down a lot if you're frequently manipulating the same data in multiple threads, because synchronizing access to the data adds overhead. It's only when tasks are largely working on independent data that multithreading shows its benefits.