Sure, but lets face it. Keeping in contact can't be done alone.

Ive had a friend for example who had to leave the country because of his dad.
His dad was very sick, so my friend went there to spend the last few weeks his dad had.
While in that proces we both tried to keep in contact but he had a lot on his mind and the contact slipped away.

Weeks went past and at some point we both never actually took the step to contact each other again.
We basically moved on with our lives, I was getting graduate and
he made the decision to stay at the country after his dad passed away so he could take care of the family.

A couple years later I found him on Facebook, wich was awesome.
Now we are back in contact and we both have no hard feelings at all that we didn't kept contact.

So yea of course you can 'take' time for some-one but he also must 'take' time for you and thats something that doesn't always happen.

You can say Facebook made people non-attentive when it comes to making social decisions.
Or you can see Facebook as a different way of getting attentive when it comes to making social decisions.

In the end its about how you use something to make it useful or not.