The buddy list is a basic feature on all sites. It's an automatic. Like the #5 on your phone.
Its a feature that is on social networking sites, like facebook, LinkedIn, MySpace etc etc.
Its not a feature of ALL websites, particularly forum based internet sites, which BB is more focused towards.
Most community 'forum' based websites do not have a 'friends' based thing unless you are a paid/logged in member. StackExchange is a really good example of this, where you can join StackExchange or loging via your FB account, much like this website, such that adding friends is a members only feature.
BB allows you to login via your facebook account - im not sure if this automatically links your FB friends that on BB as well, so you might want to check that out to see if this satisfies your friend-ing requirement. I haven't logged in via my FB account, so i can't comment too much on this.