I don't agree with what this couple did, but I find the anti-posting-on-Facebook stance hilariously cynical. You could say that about anything, not just travel. "Would you have a pet if you couldn't post pictures on Facebook?" "Would you have a kid if you couldn't post pictures on Facebook?" "Would you enjoy good food and drink if you couldn't post pictures on Facebook?" "Would you have a wedding if you couldn't post pictures on Facebook?" "Would you have a garden if you couldn't post pictures on Facebook?" "Would you go hiking and camping if you couldn't post pictures on Facebook?"
People have been doing all of the above before Facebook existed, and they will continue to do those things after Facebook is gone. Also, I do like looking at my friends' travel albums on Facebook, so I certainly hope they don't stop posting just because they're worried to be seen as bragging. Likewise, I'll post what I like on Facebook, be it travel, food, or cats, and people can choose to look at them or not.
But yeah, travel cheaper if you can, and don't go into debt for a holiday.