"... especially in the US where people's lives are destroyed and horrible politicians get into office due to supposed authorities calling people names on the internet."

For someone railing against unsupported assertions, that's a whopper. We can stipulate horrible people have gotten into office and that people are calling other people names on the internet, but the arrow of causation is not at all clear.

Addressing your point more directly: I don't think the problem is people making insufficiently footnoted comments so much as readers accepting things that align with their predjudices uncritically. As such, I don't see what is gained by attacking someone for commenting in a casual style.