The eternal-september; or its international equivalent, kills things because the nature of the public you are interacting with has changed.

These issues with reports and junk contributions come about because there is a huge payoff for pretending to be part of the community, but the benefit from actually contributing is generally less direct.

I dont think you can solve this with "friction", because the people you want to dissuade are more tolerant to these kinds of barriers than the ones you want invite in.