Yes and yes.
>If the former, it looks quite impractical unless there are widely trusted bulk verifiers. E.g., state DMVs.
It's happened already in some cases, e.g.: https://en.wikipedia.org/wiki/Real-name_system
>If the latter, then it all looks quite prone to corruption once bots become as convincing correspondents as the median person
How about a requirement to personally know the other person in what hackers in the past called "meatspace"?
Just brainstorming here, but for a cohesive forum, even of tens of thousands of people, it shouldn't be that difficult to achieve.
For something Facebook / Tweeter scale it would take "bulk verifiers" that are trusted, and where you need to register in person.