There are a lot of factors which may explain why forums have not been as popular as they once were. In the tradition of all things internet, here're my top reasons why. Lack of a common account eco-system. Facebook (FB) has been steadily expanding its sphere of influence by integrating its accounts with other social media platforms. This means you don't need to setup an independent and separate account and remember yet another password as is the case of a web forum. Security controls. Let's face it, open-source web forum software cannot be as secure as FB's security system. FB has a lot riding on security of user's information. Expansion of FB Communities. Facebook has evolved to the point where they have a marketplace which is arguably better than traditional local alternatives like Craigslist. As compared to web forums, FB groups allows multiple options for secrecy and administration which is a crowd based administration model free of charge for its users. Multimedia integration. Although some forums will allow you to upload images and sometimes short videos onto the web server its hosted on, FB has a lot more bandwidth to offer an unlimited amount of multimedia to be added and integrated within groups, pages, and posts. Anonymity. As much an upside as a downside. We live in an era of Internet trolling and as the impressionable youth discover online bullies, they exist in cyberspace as well so FB's has controls which allow for law enforcement to handle extreme cases of this. On a typical web forum there is usually a part time hobbyist maintaining the site so logs and other information are harder to track. Because of this, web forums do not attract a lot of content authors because they don't want to deal with bullies or if they're new, deal with veteran users with boilerplate "google first" answers.