@fnusnu
You might be fine with making your contacts list public and it being shared, but how about all the people listed on it? Or photographs - do you ask permission from everybody included in the picture before sharing? I have never used facebook, but I know from friends who do use it that my phone number, email address and several photographs that include me are there. When you add in the likes of Apple, Google and all the rest, I suspect that the number of people who have my contact details is mainly made up of people I don't know.