So yeah, I guess they aren't "impossible" to live with out in the strictest sense. But having lived with them for some years and then going cold turkey becomes impractical to the point of impossible the next time you organise some get together and dont have a way to coordinate with a large group of people. Don't get me wrong, that is a really excellent feature of FB/Google tools, which is what keeps people around in spite of the creepyness.

Like you say, lots of people get by fine without, but is that because you have never really used them so much as to become dependent on them? The world worked without the internet, but try taking it back to that place now and you'd be laughed at!