On the other hand, I was told by boost project that my one line fix for a typo was "waste of maintainer time", so it seems to vary on per-project basis :)
There are software projects out there, even highly used ones, that only use Github to mirror their SVN repository (or some other yesteryear source code system). For those maintainers these PRs do take up more time than they contribute though.
I can limit interactions to non-new users.
I can limit interactions to users that have contributed before.
I can limit interactions to users that I have manually whitelisted in my repo.
Unfortunately, only one of these can be active at a time, but the options do exist now.
Go to your repo -> Settings -> Moderation Settings -> Interaction Limits