Accountable for users giving it a malicious use? What, like if people sell drugs through it? I haven't seen that. There are probably people that want better moderation from Facebook, but that also risks being seen as censorship.

What I have seen people try to make Facebook more accountable for is the under-the-table handling of data of their users, but that's not users making a malicious use of Facebook.

Facebook hosts and runs their platform, if they gave me their code they wouldn't be accountable for what my users did with it.