At the time, from what I saw, it wasn't actually so bad. I would consider it distasteful, even offensive at times, but from what I've seen they weren't organizing harassment or bully campaigns. The general attitude was something along the lines of "haha, what a loser/idiot", and in some of the more tragic cases it was also followed up by "but this is very sad to see :-(".
I don't recall seeing the targetting of people based on their sexuality or gender identity. The range of opinions on things like GamerGate were fairly diverse, but the main attitude was "petty manchildren crying about muh gamez".
Plenty of stuff I disagreed with, and plenty of comments that I would describe as being made in bad taste or downright offensive, but my take-away was that, at the time, the description of a vile nest of horrible reactionary alt-Right bullies as some on RationalWiki claimed it, was pretty off the mark. We had plenty of trolls on RationalWiki for sure, and some pretty vile ones too, and most people on KiwiFarms thought they were just a bunch of losers. Yet, somehow, they were still attributed to KiwiFarms shrug.
I don't know the details of the this situation, and it's been six years so all sorts of things could have changed, but based on my previous experience I'm very hesitant to immediately jump to the conclusion that it's a "forum of people that bullies vulnerable people until they kill themselves" because I've seen all sorts of hyperbolic claims before and found them untrue. Maybe it's correct this time, but ... yeah. Fool me once, fool me twice...
And if this comment wasn't controversial enough already: I feel this stuff is sometimes taken way too seriously, and that this is actively harmful to people like Near. I completely understand why they would feel upset if people say ugly things about them, but a lot of this crowd seems to provide only validation and recognition for being upset, and not enough "just some rando losers on a forum, get over it and stop crying". I don't think this is helping and an (unintentional) but vicious feedback loop. The fact of the matter is that the world has ugly people saying ugly things. This has always been true for all of history, and will always remain true. It sucks, but we can't change that. You can either shrug at insults or slurs, or you can become very upset with it, and it's absolutely not a given unchangeable fact that "getting upset" is the only possible action.
I don't want to put too much weight in this letter as it's obviously written from a place of grief and anger, but it mostly seems to externalize Near's problems to KiwiFarms. It seems to me that their problems were mostly internal, as is usually the case with people suffering from long-term depression. Perhaps the external KiwiFarms "pushed them over the edge", but that's not the same as being the primary cause. This is important because if you focus on the wrong things you're not going to solve whatever problems you have.
However, no matter what I say here, or what the facts of the case may be (maybe it is as bad as claimed, maybe not) I think ... none of that will really matter here anyway :-/