Why do some celebrities who decide to make their own Facebook accounts allow you to follow but not add?

[Emily]

I've noticed that some rock stars I like have Facebook accounts i.e. David Ellefson of Megadeth. They allow fans to follow them with the new follow feature on Facebook but not add them as friends on there even though they do have friend lists? Why is that? I'm not interested in stalking any celebrities. I'm just curious.

[Kevin]

theres a number of friend limit, which is 5000, while facebook doesnt impose any limit on the number of followers

[pri✍]

Beside the 5000 friends limitation and no limitation on followers as explained by Kevin; celebrity do have the right to talk in 'private' with their friends in life without exposing everything to Public, don't you think so?
While you know, FB actually 'rules' us to only add friend if the person is really someone we know in real life, thus the 5000 limitation is ruled out.