Yes, it is a rather important issue. Even though Zuckerberg claims the net effect of Facebook on the election was positive, he's had to promise defences against nation state actors trying to subvert democracy; clearly, his notion of Facebook being "a platform for all ideas" isn't quite as all-encompassing as it seems.
Twitter, a minnow compared to Facebook with "only" some 328 million monthly active users, has similar problems with troll-bots while pondering doubling the size of tweets.
Hundreds of Russia-linked Twitter troll accounts that tried to foment anger against the US National Football League players' take a knee protest have now been deleted, but how many more are there left?
It's hard to imagine it never occurred to the Zuck, @jack and @biz that technology-driven media platforms that profess no specific values and have enormous reach can be perfect tools for negative communication, bullying and information warfare.
If the Chinese get it, and not just ban but block Facebook, Twitter et al rather than risking their population catching undesirable "influenca" from them, you'd think the social networks would have some inkling as to the power, positive and negative, that they wield.
There is no such thing as free speech where anything goes anywhere in the world. That inconvenient fact clashes with the social network business model, a numbers game with as few barriers to entry for users as possible, and a fervent desire to keep people on board once they've joined no matter what.
This is why you won't see anything Nazi-related on German Twitter where such material banned by law, but it will be visible elsewhere in the world, and the accounts responsible for it remain active.
Such a reactive approach to limiting hate speech and misinformation is guaranteed to anger politicians profoundly and goad them into drastic measures such as content blocking, splitting up the companies themselves or blocking them as China does.
The social networks are living dangerously here, and may end up having to dump the naive goal of being platforms for all. It's never worked in the history of humanity, and technology isn't going to fix that.