Robin Dunbar looked at the capacity of human beings to maintain relationships. He found that our brains can only maintain about 150 friends at a time. So from the Stone Age on, groups have self-organized around the 150 limit.
What's going on is that your brain is connecting all the pieces of relationship between yourself and the other people in the group. You hold in your head how person one will interact with person 37 and with person 90 and with 148. But if you get beyond 150 your brain can't keep up anymore. This has been proven again and again for groups of people throughout history.
What's been in question though is how social media has affected the equation. Recently a study was performed on Twitter users to examine how many relationships people could maintain. The finding was shocking in its normalcy. The limit for social media: the same as for real-life groups, 150.
What this means in practicality is that, even though you have more than 150 friends on Facebook and followers on Twitter, you can't maintain a relationship with more than 150 of them. You may have contact with hundreds, but the real connection of two-way conversation and interaction only happens between the smaller group of friends. If you look through your friend list or your follower list you'll find that it's true. You may have as many as 200 or a few a 100, but you'll fall somewhere in the 150 range.
So when you're looking at connecting with people through social media, remember that what a friend shares is important. You can only be an important voice to about 150 people in your life. Beyond that your words start to get lumped in with acquaintances, advertisements and news sources.
Really invest in the 150 that you are connected to. Choose them well and cultivate those relationships. You have the ability online to stay connected like never before -- but only with that smaller group. For the larger group, don't try to push the relationship beyond what it will bear. Treat them like acquaintances and expect to be treated the same. Let someone else be that important, friend-voice in their 150. Your brain can't handle it.