Some solutions apply, but solutions aren't necessarily the problem. In the past, running a forum wasn't that hard - get a server with PHP and a database and install your choice of tools. You could do it yourself or, depending on the size of the community, with a small set of volunteers. That still fundamentally works today.

However, in today's legal landscape I'm not interested in running any service involving user-generated content that's not guarded by an LLC and an army of lawyers. No technology can make a dent in the costs that affect my decision to run a forum or not.