> That's like saying, if you believe someone's defamatory statements, that's on you, but the speaker is innocent.
Not really. Being mistaken is not the same thing as being defamatory. If someone is honestly just incorrect, and you go parroting what they said without independently verifying (especially if the person is a pseudo-anonymous internet commenter and not a subject-matter expert) then frankly that is entirely your fault.
Modern life demands critical thinking skills.