I'm actually generally not a fan of "drive-by" PR's.
Unless the drive-by PR is fixing a simple bug in a simple way, then the contributor really should've opened an issue first. Doing otherwise is rude imo.
This is actually open source etiquette that I'd like to see encouraged more in the future. Something like "If you've never contributed to this project before, then open an issue first". I understand that this can be explicitly placed in a CONTRIBUTING.md file, but I think that this should just become common etiquette that we all follow and understand.