The thing is, they generally beat up those advocating genocide against people who don't look like them.
Many problems with this.
Antifa wants to beat those people up, but there are, at most, a couple thousand such people in the entire country. For argument's sake I'll give an overly generous estimate of 10,000 (KKK membership was 3,000-8,000, last I checked). In a population of 330 million that comes to 0.003%. 3 in 1,000 100,000. A virtually non-existent fraction of the population. So when they start throwing blows, there a huge chance that they've mistakenly targeted an innocent.
Worse yet, if you object when they beat up a "fascist" that is taken as proof that you are fascist as well. Because Nazism is completely indefensible to anyone that is not a Nazi.
We have a comprehensive set of rules in place to determine what misdeeds society can and will address punitively (the courts), and more rules to keep that system from arbitrarily lashing out at innocent bystanders (habeas corpus, presumption of innocence, yadda yadda).
And at the end of the day, we've determined that Advocating for things is not a punishable offense. Let them advocate genocide in the open, so that everyone can see just how horrible those people are. When you punch a neo-Nazi, you don't change his mind. He'll just spread his monstrous philosophies somewhere else. And when he spreads his absurdities, you will have no opportunity for rebuttle because you aren't there.
“The trouble with fighting for human freedom is that one spends most of one's time defending scoundrels. For it is against scoundrels that oppressive laws are first aimed, and oppression must be stopped at the beginning if it is to be stopped at all.” ― H.L. Mencken
They generally beat up people they claim are nazis. These days, you are typically accused of being racist just for being conservative.
They also tend to get violent when their targets are disarmed and/or when the police are present to control it, which is cowardly.
Now, even if someone is a Nazi, besides the fact that people like myself are accused of being Nazis often even though we are not (I'm pro-gun and my boyfriend is not white and yeah leftists sure don't like that I'm more libertarian), you either believe in following the law when you strongly disagree, or you don't. If you are going to punch a nazi, sign a medical waiver, and fight fairly.
There are so many laws that are not followed by both sides because people think oh I know I'm right so this is an exception. The virtue is to treat people equally even when you do strongly disagree.
ALso, while being for genocide is obviously wrong, there is some truth to what the Right says. It is discrimination to give someone an advantage in hiring just because they are not white or male, especially when that person is an immigrant. Also I have lost my job after generously training an immigrant who was black, because they worked hard. I'm concerned with immigration, not liking to lose my job doesn't mean that I agree with everything Trump does, or that I'm racist. Of course, due to my build and body language, I have not been attacked by Antifa lol.
There's no doubt about it. All these fools do is beat people up. People that don't think like them.