It’s also helpful from the other end. As a new contributor, I feel a lot more confident making a PR if there are tests and I can show I didn’t break them.
There are a lot of benefits, like you can have a 'test' that just helps you avoid aggravating scenarios by rejecting pull requests with messy code because the linter failed. If you have to discuss how random pull requests can be improved to meet your standard you are going to waste a lot of energy.