Bold claims. Do you have any references that support any of them? Inquiring minds want to know.
The "common truth" is a bit more subjective, but I've definitely noticed people in my extended social groups having fewer and fewer information sources in common, as well as a smaller and smaller set of common beliefs. I'm not the only person I've come across who's had this impression.
The parent comment made a bunch of statements. Asking the reader to read an entire book to verify the validity of any of them is wrong.
References come with page numbers for a reason.
I meant to say that while the book js2 linked is surely welcome information to have in this discussion, this doesn't absolve the OP of the burden to back the claims with something more substantial given how strong these claims are (and, as the thread shows, controversial).