1) the core claims of Gamergate have now been shown to be overblown at best
The initial claim turned out not to be a simple quid pro quo. The person who gave the favorable mention of Depression Quest turned out to have been mentioned in the credits for the game, however. He gave a mention to a game he was involved in the development of. This is certainly less headline-grabbing than sex-for-coverage, but I don't think it's any better. Either way it's a tempest-in-a-teapot at that point... but the more people started looking, the more rot they found.
It's clear at this point that there's a group of "gaming journalists" who give favorable reviews to their friends and political allies while giving unfavorable reviews to others on the same bases. And who are contemptuous of gamers, though that's not in itself unethical.
there is no public evidence that any of the claims of harassment or threat at question were fabricated, only speculation
There's little public evidence on either side about threats and harassment. The most well-investigated threat (to Anita Sarkeesian) seems to have been from someone in Brazil who she already knew about and has been threatening her since long before GamerGate got going.
A lot of the so-called harassment is just people responding publicly to statements made publicly. That's not harassment. Dot-mentioning someone on twitter is not "harassment". Making a response video to someone else's video is not "harassment".
Do you really find it hard to believe that these death threats are genuine?
As with harassment, a lot of these so-called death threats don't even fit the form. They count things like "I hope you die" or "Go kill yourself" as death threats, when they're clearly not. Some of these death threats were actually threats and actually happened, but "someone sent me a death threat therefore my opponents are wrong and evil" still doesn't hold together.