[scotty79]

HN model works, people do downvote for you, if you are just like everybody else here. You indicate that by visiting HN.

In more universal platform such as Facebook you need to indicate who you are by subscribing to specific groups or downvoting some of the content yourself. Just visiting. Facebook is not enoug. Once you signal who you are you also benefit from other people just like you downvoting content you wouldn't like, for you.