Yeah but general purpose data centers that allow hobbyists to spin up an app or a service easily is exactly that: general purpose. AI data centers are built for the very specific kind of math that LLM's require. Even the GPU's can't even be used for something like cloud gaming, which isn't very popular anyways.
That math is very much general purpose. It's just linear algebra under the hood, and linear algebra is a wildly useful toolkit with an unbounded set of potential applications, including many applications other than LLMs. That's how something developed for gaming evolved into something used for text processing and generation. For example, we have barely begun to scratch the surface of what we can achieve with robotics, and I have no doubt that further advances in robotics will generate an enormous amount of computer vision work that GPUs are extremely well designed to handle.