Or, you know, the user is not a developer. Or is unfamiliar with Python, or their test suite, or git, or…
It is perfectly possible to be good at reporting bugs but be incapable of submitting pull requests.
By asking users to provide reproducible test cases, you can massively reduce the amount of work you have to do. Of course that means 90% of bugs will never be reported. But since you don't have the resources to fix them anyway, why not just focus on the bugs that can be reproduced and come with a test case...
It’s your prerogative if and how you want to limit the amount of people who can contribute, but I was explicitly replying to someone claiming that a person’s inability to code is in any way related to the validity or importance of the bug.