I find it definitely started around game journalism and integrity, Zoe Quinns case was honestly just the last straw for some people. 
Plus the fact it involved multiple Journalists and not just one, also helped get her more attention. I think those who say "This is about the sex scandal, why isn't IGN being attacked otherwise?" was covered pretty well by Dipper in that this case specifically IGN was out of, but IGN has been the constant focus for several years. It's not as if IGN was stayed immune for criticism for bad journalist tactics overall.
+IGN for a long time was known as a Big Dishonest Corporation, them being dishonest was common knowledge so most people universally knew to ignore them. Zoe Quinn's case partly hit as hard as it did because the Journalist involves were smaller ones, those who thought did remain honest, those we didn't expect to be dishonest like IGN was known to be.

However, I that's all just in regards to how this all started. I will more than admit that at this point the issue has evolved past Zoe Quinn and Journalist Dishonesty and has grown to involve feminist/sexism attacks on gaming over all, plus a lot of anger over essentially being told "Gamers don't matter in Gaming". What started as a final trigger explosion against dishonest journalism has expanded into a far wider and more complex topic.