None of these pull requests (PRs) are getting accepted, but someone has to manually check whether they are the right PRs or wrong PRs. With this spam, it becomes extremely hard and time-consuming. Remember, most of these developers are not getting paid by any company; they are open-source developers. So, this is literally a nightmare. 

 I'm unsure as I never tried this on github before, but: Isn't it possible to limit by default who has the permission to even create a PR on a particular project? We used gitlab internally, selfhosted, for ages, and even there in a rather small team we had settings like this to keep things somehow "controlled"...  

 There is.