Because I'd have to fork, wait for the Github client to process the fork, find the source file that produced the error, fix it, commit, push, then go back to Github to create a PR. PRs are overkill for typos on a project I don't develop on.
You can do all of this from the web interface. There's a pencil icon on the top right of the document. It will let you edit the file then create a fork and PR
