I remember when we were all moving from Yahoo to AltaVista as a search engine and using it to look up people we used to know, hoping to get caught up with them. It was (and still is) impossible to find the Bill Smiths in your past that way, but some people had nicely unique names. And back then, only a handful of us were online; I was the only person with my first and last name, even as late as the first few years of Google, but nowadays, my relatives take up most of the first page of results, and you need to include my middle initial to find just me. But even if you found someone you knew years ago, what then?
Used to be, you had to try to write an email summarizing what had happened in your life between then and now, and in addition to being a big chore to write and probably not terribly fun to read, it was hard to decide how much detail to go into. You don't want to bore them, but you don't want to make them feel like they aren't important enough to be worth telling your story to. You don't want to feel like one of those old Christmas letters that everyone hates, but you want to accurately reflect the nature of the relationship, whether that's former best friends or just casual acquaintances. All while being entertaining.
Fortunately, the endeavor of finding someone was hard enough that you probably wouldn't try to go through this whole "catching up" process very often anyway. But nowadays, finding people is not nearly as hard as it was. Google is sure better at it than AltaVista ever was, but even Google can't find Bill Smith. However, Facebook probably can, if Bill has chosen to be on it, and by now most people have. Which could mean you have to write more versions of that email, and have some of them even harder to pin down the right level of detail, since you'll be finding friends you know less well or haven't known for longer.
Fortunately, those same social media provide an alternative. If you have updated your profile, and you are fairly active at writing status updates and posting links and even notes and blog posts, then once you friend someone, your wall can be a way for them to catch up on your life. It has a few advantages: they can read as much as they want and skim or skip what they don't, so get a more or less superficial view at their own preference; you don't have to go to extra effort to make it happen; you don't have to try to figure out how much detail one person or another would like to get; and it happens by a more organic, unplanned process. Of course it has disadvantages too: they can have a superficial view of you but they probably can't get a very deep one unless they actively participate by asking questions or drilling through links and reading back posts; things that were important, or that might interest them, might never come up in the scattershot randomness of whatever happens to get mentioned in your posts on any given day; and people could easily conclude you don't care enough to send something personal (a statement which means less than it seems to mean, but which is still going to be cited as revealed truth for generations to come, I'm sure).
All in all, it might mean a lot of people will get only a superficial view of you, but that superficial view is at least the seed by which a deeper view can be made available. Many won't take it up, and that's their choice. It's not a bad thing if one person chooses to read my blog posts and another doesn't; it doesn't mean I'm caring too little about reaching out to them, or they're caring too little about reaching out to me. The fact is, while people may bemoan the intangible, evanescent nature of the "connections" the Internet brings, in most cases, the pre-Internet alternative was no connection at all. It's easy to make fun of how a Facebook-friend isn't the same as a "real friend" like we had them back when I was young and had to walk to school uphill in the snow. But the fact is, for most people, Facebook-friend isn't instead of that other kind of friend, it's in addition to.