When I was a kid, everybody's name, address, and phone number was published in a phone book. Why does everyone feel like that's private information today? For some special people, yes, but for just about everybody, it's fine for others to be able to contact them.
If I wanted to be kept hidden, I'd have to be careful who I gave my secret information to. If I trust my friends, and they carelessly give it to Facebook, that's my fault for carelessly trusting untrustworthy friends.
The key difference is how easy it is to correlate different digital datasets. The phonebook gives you name, address and phone number. Call logs give you pairs of phone numbers. Together you know who knows who. Add in the yellow pages and you know who called the suicide hotline. Mix with taxi data and you know who visited who, what time. And who went to an abortion clinic. Or a place of worship. Or who knows more than ten people that regularly worship.
Etc. Getting all that for everyone as opposed to a certain targeted someone is much, much easier with digital records.
[ed: this is why many countries have had strict rules on digital databases of personal (not just sensitive) data a long time, well before the GDPR. The amount you can learn from "simple" correlations of even public data can be staggering.]
Back then long distance was expensive so you didn't get scammers outside of the US calling you. Local police are currently unable to deal with the deluge of foreign scams making protecting your private information much more important.
If I wanted to be kept hidden, I'd have to be careful who I gave my secret information to. If I trust my friends, and they carelessly give it to Facebook, that's my fault for carelessly trusting untrustworthy friends.