We've got hate crime laws even though we already have murder, assault and harrasment laws. Might just be another way of tacking on extra punishment due to the nature of the crime.
The difference between libel and "cyber libel" is just the medium. Arguably it'd be more like the difference between how the 1st and 4th amendments should be applied in your home vs. on Facebook. But like the GP, I'm not aware of specific cyber libel laws or charges.
Non-hate crimes don't have this effect. They don't make a group feel afraid, singled out, and specifically targetted.