FPH was unconstructive and blatently offensive. I don't see why people were upset by that being banned. Thoughts should be open to criticism however.
People were upset that FPH was banned and other, far more toxic subreddits were left untouched. If you are going to start moderating the content on your site, you need to moderate all of that content consistently. Also, the great thing about that subreddit system is that people who think a certain way will stay in their own subreddits. There are really horrifically racist subreddits, as an example. If people tried to say those sorts of things on another subreddit, they would get shouted down so fast and likely banned for good measure. If you don't want to see those kinds of things, don't go to their subreddits.
FPH got onto /r/all regularly, no other hate sub achieved that. They constantly posted pictures from other parts of reddit to make fun of those people, There's no way a system like that doesn't leak. The problem is that subs like this allow people to feel that their ideas are validated. You cannot argue that hating on a massive group of people is normal or okay.
As long as people are around we will find some reason to segregate into groups and hate one another. Historically, hating large groups of people is something humans are very good at. Is it normal? Yes, in that the "us-them" mentality has been around for a long time. Do I agree with it? No. Not at all, and we should all as individuals try our best to eliminate that "us-them" mentality from ourselves. You're right, I can't argue that hating on a group of people is okay and that is not what I'm arguing at all. Where did you see me make that argument? In everyday life people will hate you for no reason whatsoever. As a brown guy I get racist comments hurled at me on the street all the time. Is it okay? No. It isn't. However, since when did "sticks and stones" stop being applicable? People can say or think what they like. Thought crime doesn't exist. As soon as it turns into action is where problems arise.