If they really, really want to fix 99.8% of the problems with hate speech (and many other issues), each user needs to agree to have their real name, home address, email address, and phone number available to the public, in their profile. While what I've just said is completely absurd, for almost everyone, it's the anonymity that empowers people to say the absolute worst things.
Why don't most people in the checkout line (queue) at the grocery store act the same way they do in a traffic jam on a roadway? Because they're much more likely to be held personally accountable for their conduct. I wonder how much traffic would change, if our name, address and telephone numbers were required to be posted on all sides of our vehicles?