Yes, numbers are more convenient than spaghetti
1. Hate is destructive and irrational. It only produces more hate and suffering. It is a natural emotion to hate back. But rational humans should be able to not be controlled by their emotions and understand that evil and immoral actions against people you hate are still evil and immoral actions.
2. Easier to hate them this way, isn't it? It is also easier to say that all of those are losers and humanity would be better if all those bigots just disappear. That they are incapable of loving and no one loves them. That there are no doctors, scientists, engineers, artists among them... That many of them still do more good than harm.
3. Nobody views fascists as martyrs and protectors... Who and why joins them then? Also, political ideology is a slightly different beast and differed from the ideas of that ideology.
4. Inciting violence is not tolerated and is illegal. But let us be honest, you don't want to limit censorship to that. Phrases like "*insert homophobic slur* are sinful disgusting deviants." don't call for violence but I have no doubts that you want those banned, too. There are also gray areas like Rolan7's comic, which can be interpreted as inciting violence.
Personally, I don't care much about stuff like "You are a servant of Satan, who is beyond redemption and should be executed." because the chances that person actually means it and is ready to act in this way are really, really low.