"I say we forget this business and run."
This is exactly why it's a problem. Discord, Telegram, Skype, and so-on linking is something of a grey area on its own, but in regards to general Forum Policy and whatnot it'd be a losing battle not worth the effort. A couple sites make triply sure to cover their bases for legal stuff(only letting users post excerpts of news articles, for example), but there's enough wriggle room by default typically for a site to go "It's not on us" if it turns out somebody joined a private chat group or chose to meet up with somebody using information that was shared on their servers and turned out to be Bad News.Considering people offer support and post links to discord servers without this category, I feel like it wouldn't make that much of a difference to add it.
That calculus... changes, when you make a subforum that's specifically created for having users air their dirty laundry and vulnerabilities in it. That calculus changes even more when said subforum is an official subforum / thread... on a website's official forum. Your potential for somebody to take a long look and go "You were negligent" is a lot higher. You can get around this by generally showing that your moderation did as much of a good faith effort as could be expected to prevent exploitation... but therein lay the other problem. FA is not a minor site. It has money. It was, indeed, recently sold for presumably a good deal of it. Its standard for "good faith moderation efforts" is going to be higher than many sites.
Consider, if you will: We had two self-avowed domestic terrorists / extremists banned on FAF approximately in the last year. Not "Hrng wrongthink" 'extremists', self-admitted members of literal "Defined by the FBI and international law enforcement community as terrorist extremist groups" groups. We also had a returning familiar face outright doxx one of our users and try to intimidate them by sharing the doxx'd information publicly on the forum. Just as three immediate examples from the last year. So we know people have their eye on FAF, as well as that they're already fishing for user information. And not only do we know that, there's staff activity logs showing that they're aware of it too.
The "good faith moderation efforts" required to allow as much would be... more than many people here would probably like. Including staff. And while they could skimp on as much, I can't imagine Dragoneer's in any sort of financial position at the moment to play that roulette instead of playing safe.