If the validation process to obtain a certificate is rigorous then you have little deniability if and when you are held accountable for any shenanigans. Where I work, if the process to obtain a certificate is rigorous enough, certain entrusted CAs can issue certificates with legal non-repudiation (legal signature) and identifying power. This is written into law. You can bet your car this will create tons of case law when GDPR lands.

The EV-cert doesn't help twitter or facebook (other than making them seem more trustworthy), it doesn't provide any extra cryptographic or operational security, it helps the user better ascertain who is accountable and where when the shit inevitably hits the fan.