“Trans panic” is (still) a legal defense for murder in 49 out of 50 U.S. states. A good part of the reason for this is that many people believe that trans women are actually men, and thus cis men who feel they were “tricked” into bed by them are justified in killing them.
This is why deliberate misgendering and hate speech go far beyond just “hurting people’s feelings.” This doesn’t mean that the government gets to lock someone up for making sexist or transphobic comments. It does mean that such comments can be grounds for banning someone from online forums or, in some cases, firing them from a job. Social ostracism is a legitimate response to hate speech.