Twitter, Facebook, and all of the other instant crap gives every appearance of being an absurd waste and abuse of technology.
Why anyone would rely these annoying gimmicks for anything is beyond my ken. Especially in lieu of a simple phone call, preferably from an actual telephone, or merely showing up.
Rely on? No.
But make no mistake it has it's place and it can generate revenue, I know it has for me. More and more people communicate through the computer rather then in person or on the phone in a verbal conversation. I would say 90% of my business is communicated through the computer in some shape form or fashion. It just allows for more flexibility on both sides with regard to communication.
There is a saying that is quite appropriate for this:
"Change with the times or the times change you."
Now, I don't know about your specific situation, you might have a reason (or reasons) why FB/Tweeter etc are irrelevant at this stage in the game. However, if you are just coming into the business world (doesn't really matter what business at this stage) and your are going to be in the world for a long time to come, it's something that you should be using. May not have to understand it. Hell, you can hire someone to do that for you, but you should at least be using it especially the longer you are going to be out in the work force. It's just way to underestimated. It really is.