In the T-shirt example if you left the program as-is but then decided that tackling abuse is a separate topic, think about what that would look like: Every maintainer would now not only have to read and close the spam PRs, they’d have to go file an abuse report for every single one of them. Now you’ve put even more work on the maintainers and created an additional burden of reviewing reports, all without clarifying the program to discourage abuse from the start.

This is why it’s necessary to structure a program clearly such that abuse-level or low effort inputs can’t easily claim the rewards.