I'm not a fan of this change because:
- It significantly reduces the pool of repos that you can PR to. I've contributed to repos which haven't explicitly opted in to Hacktoberfest this year and in the past as well. Repos in which I am more comfortable contributing in than some random GitHub search result for the "hacktoberfest" tag. With this change, I am forced to look into those, or convince the maintainers to tag their repos.
- For intermediate or experienced programmers it voids the whole event because the vast majority of OSS projects won't get involved.
- After the spam fest that this year was, people aren't inclined to add the tag to their repos because it paints a target for spam over them.
- Maintainers can now gatekeep your contributions, so even if it's something meaningful the maintainer can deny you a +1 PR for your work. It can be frustrating spending a non-insignificant amount of time to get the t-shirt the right way and then have that time nullified.
- It doesn't address "hello world" spam repos. In fact, it encourages them because of the reduced amount of repos available to contribute to.