Because to be frank, back in the late 90s up to the early 2010s, stories about rape weren't as taboo as they are now. It was actually rather common; a cheap way to titillate the audience while building up character drama and sympathy. The trope of sexual violence hardening a character who experiences it or witnesses it was rather common in that time, especially for edgelords wanting to write "mature" stories, or authors cynically trying to grab the attention of young males.
For all of Linkara's whining about comic authors using stale tropes or "objectifying" women, he sure made use of a trope that edgelords and horny teens loved to fall back on when making his comic.
Not that having rape in a story is wrong, or anything. I mean, if you're writing a story, and having the story depict or talk about rape is where you think it should go, then more power to you. It's just that Linkara having stories of rape in his comics is awkward when he claims to be a feminist, especially when we have the feminists to thank as to why rape stories are taboo because they "trigger" people.