Robert Cailliau together with Sir Tim Berners-Lee worked on the World Wide Web creation project at CERN. He explained in an interview from 2010 why he would not use Facebook:

I can get in, but I can’t get out. I don’t know what happens to my data.

He also hates JavaScript.

You don’t build a house by putting one brick on top of the other, but that is what you do with JavaScript