

It is their problem until the second they submit it, then it is the project’s problem. You can lay the blame for the bad actions wherever you want, but the reality is that the work of verifying the legality and validity of these submissions if being abdicated, crippling projects under increased workloads going through ever more submissions that amount to junk.
What is the solution for that? The fact that is the fault of the lazy submitter doesn’t clean up the mess they left.
I do think that some projects will fare better than others, particularly ones like you mentioned, where the team is robust and capable of handling the filtering of increased submissions from these new sources.
I believe we are going to end up having to see some new mechanism for project submissions to deal with the growing imbalance between submission volume and work hours available for review, as became necessary when viruses, malware, and spam first came into being. It has quickly become incredibly easy for anyone to make a PR, but not at all easier to review them, so something is going to have to give in the FOSS world.