Of course chacha1-7 is a thing. Just not for cryptography. I used 4 rounds of salsa to create random-looking numbers just for fun (4 rounds is what you need to get good diffusion), and I know for a fact that I am not alone in having the idea.
The reason nobody uses it like that is that it is slower than most other PRNGs
The reason nobody uses it like that is that it is slower than most other PRNGs