The political satire of the 18th and 19th centuries was savage. Had Twitter existed back then, it would be no less uncivil.
Human nature + anonymity is a bad combination, I’m afraid.
The average random person you meet is at least “nice”, not it be confused with “kind”, and “niceness” is performance. It’s focus is not ruffling feathers which is not inherent kind, as kindness may do so.