The argument that just because a third party has the information, that negates the privacy of the individual, is such a facetious argument, that it is not funny. Your Doctor, is a 3rd party, you Priest, Lawyer, Accountant are also 3rd parties. Does this then negate the privacy of your conversation? Or the fact that you even had a conversation?
What about your Location? Courst have ruled that placing a GPS tracking device is illegal with out a warrant. The metadata from cell phones, includes your location. Is the location of my daughter, or wife 24/365 a matter of public record?
The arguments for this invasion of privacy are specious at best. It is a clear breach of the 4th amendment.
Most people do not realize how much information is located in the metadata. In many cases you don't even need to know the conversation to know something vitally private. If my daughter made a call to an abortion clinic, do you consider that private information? Simple joins of database make that metadata, extremely compromising.
As to 3rd parties such as Facebook, I volunteer as little information as possible. I "KNOW" they will sell me down river.