For sure, Facebook allows you to keep up with distant family and friends. But my take is that devoting a lot of mental and emotional energy to distant relationships comes at the expense of time that could be spent developing local relationships, which can be more important.

I think a good metaphor is after you've broken up with someone, it can be healthier not to hold onto to a lot of photos, memorabilia, and so on associated with your ex. It's not that you are throwing your ex away; you're making room for a new person.

I've sometimes observed people are so caught up in the lives of old school friends, old colleagues, family and such that they don't have room for new, local relationships.

I think many people can use Facebook in a healthy way. The same can be said of alcohol, video games, reddit, and Internet news feeds. But, for many others, all of these can become damaging addictions. A lot depends on the individual at hand.