They matter as long you're willing to enforce them, and have the time and money to do so.
In that case, you may be able to submit some form of take down request to GitHub against that project and other projects who are using your library.
https://github.com/search?q=bouk%2Fmonkey&type=commits
edit: wow, one of the projects that depended on your library was arduino up to 2020. https://github.com/arduino/arduino-cli/commit/09b4e8804fbd61...
edit2: was also used by AWS up to last week when they removed it. https://github.com/awslabs/karpenter/commit/d84365e8c44178ea...