"i don't understand why posters on this thread really need to understand gamergate at all. "
Because the person in the OP is not accusing one person of sending the abuse but a group of people. Millions of people who call themselves gamers. She used the hashtag #gamergate. One person sent her those messages. The gamergate hashtag is a grassroots movement of people who are just gamers, that is people who enjoy playing games a lot!
No one deserves to be abused or harassed. I myself have stood up for Sarkeesian against the minority of people who abuse her, even though I disagree with her and know the stuff she writes about games is rubbish.
In every group of 100 people there is statistically going to be one who fits the description of a psychopath. So in the millions of gamers there are going to be a few bad eggs. Letting a minority of psychopaths who enjoy the attention they get from frightening people, dictate the terms of the debate, is a race to the bottom and in no one's interest.
Sarkeesian is an ideological radical feminist who see's harm in video games when there is zero evidence to support this. That's what people legitimately argue with her about, but she directs peoples attention to the psychos. Sarkeesian appears to think legitimate challenge in the theatre of free ideas and free speech counts as harassment. It doesn't. As in the video, gamers are categorically anti-harassment and they themselves stamp it out where they find it. As you will see in the first link I posted, it was a journalist sending abusive tweets to manufacture outrage.
It might surprise you to know that a huge amount of men receive death and rape threats too. And also that many women on the internet don't. I am a very vocal person on the internet and Twitter and Ice received zero threats of this sort. I've been threatened (or attempted) by radical feminists for not following party lines. But not by anyone else.
I'm pretty sure most of the people lurking on here will have the intelligence to see the difference between real people fighting for the right to have a dissenting voice against powerful ideologies.