Notwithstanding his mental health (which at this point, I think, remains to be confirmed), we know these online communities exist, we know what they’re about, how they reach people, and their goals. I don’t know what’s served by ignoring the broader context.
Pretty accepted right now that he had mental health issues. I guess that may make him more open to influence from batshit beta male stuff like this "incel" hatred of many and women who are able to get laid. The wider linkages to MRAs alt-right etc. Is nuts though