Although in the USA we're used to the notion of having a right to confront our accusers, that only applies to a court of law. Responsible social media platforms will maintain the confidentiality of all reports, and if they don't, I assume they could be held liable for damages, should anyone "come after" anyone. I don't blame you for hesitating; people can be nuts online. I'd LOVE to know, sometimes, but I recognize that the greater good is generally served by maintaining that confidentiality and having some means of appealing, should we suspect a coordinated trolling attack against US. Facebook, Twitter, LinkedIn, and Medium will not tell a person you reported them. Don't mention it to anyone, don't confirm that you've done it, don't ask others to join you in reporting them. If you feel they're a real danger to someone, contact law enforcement. They'll also investigate and maintain your confidentiality unless it comes to a criminal action and you're pressing charges.

I'd hesitate to confront someone directly. Even if I'm just filing a DMCA take-down request against a copyright violator, I send that to their web hosting company. I no longer try to have a grown up discussion with people on the internet if I don't know them and they seem like they MIGHT be real criminals.