I agree with this and the quoted post, but i echo chambers and self selecting news are nothing new. Before social media it was the newspapers.
A quick question, the BBC have to be impartial in their coverage of political partys as part of their public funding, do other TV broadcasters have to follow the same impartiality laws?
Social media and newspapers are not alike.
You buy a newspaper knowing its political slant and you read stories with that in mind.
Social media and blogs make it possible to hide that political slant before the user starts to read. If all they read is written by users with one viewpoint (because that is what's fed to them) then it takes a very strong mind to say 'actually I disagree with everything my friends are telling me is true'.
Social media is the equivalent of being force fed whereas newspapers are a buffet (admittedly, a more right wing buffet).