Is there any tangible benefit to being on Facebook?
None what so ever 
Sorry but i've met up with old schoolfriends i might never have done. Folk move all around the world as i've found out. It also has it's own MSN thingy for private chat, apps for free silly games & LOADS more to pass the time.
Tangible, yes. Easy to be condescending?
? 
I suppose that communicating by way of Facebook is better than not being in touch with people at all, however I've never, in my adult life, had the apparent luxury of having 'friends'
I've had colleagues and acquaintances yes, but friends, no - and any people I do need to communicate with, unconnected to the job, I do so by letter or occasional e-mail - voice communication isn't really appropriate in most cases.
Aside from that, this forum is the extent of my regular foray into the world of public communications, Facebook and the like are off-limits so perhaps I'm not really in a position to comment with any degree of competence.