Hate is a short-cut to building an online community.
Arguments are easy to get sucked in to and hard to walk away from. If your online community is filled with arguments, you’re going to get people joining quickly and visiting often. It’s addictive.
But you attract the lowest common denominator of people. You attract people that don’t want to achieve anything. You attract people that love arguing.
Have you seen the “We hate [celeb/group name]” groups? They’re popular, but they never get much done.
A hate-filled online community is a live grenade. They will always be looking for people to hate. Sooner or later, they’ll target you or someone smart enough to report your online community to your ISP.
Then it’s game over.