>One example I've seen of a bot automatically creating PRs is dependabot to automatically update dependencies, but in my opinion it adds way more noise than value. Running a command locally to do the updates is just as easy, without any of the noise.

It's just that you need to set up some kind of recurring reminder to do that kind of work, which ends up also being noise, and the work is a chore, nothing more. IMO the noise of a bot emailing you a ready-to-merge PR (usually 1 click) is better than the noise of a calendar event with at least 3 manual steps.