You're not wrong at all on that, however, the quarantining and banning of hate communities happened before the removal of any and all NSFW subs from /r/all. The hate groups were largely getting restricted well before that. I realize they're two sides of a similar coin - but there were different motives behind the shifts. Recall also, that most of those groups getting quarantined and banned were not NSFW communities.

Nobody was using boobs or twerk videos for hate speech. A 4K/60FPS version of that gif of Alexandra Daddario wasn't being used to advocate violence against political figures. That later shift was done purely for user control of content. Reddit (probably) isn't getting click shares off of imgur reposts of daddarios boobs. If they're not standing to gain, they lose every time someone leaves the front page and goes to a sub page to explore more. They also get fewer eyes on their paid content if people are turned off from using /r/all because they don't want to see said boobs. That particular move was a dollars and cents content control move only.