Reading a book interferes with "train friends" as well. Books are every bit as isolating as any electronic gadget. I LIKE the isolation of reading a book, whether on a gadget or in paper. When I want to talk to someone, I put the book down. Same thing with any gadget.
And thank God we have "personal music" via headphones rather than being subjected to somebody else's boombox or transistor radio.
And frankly -- I find "train friends" talking loudly to each other every bit as annoying as folks talking loudly on their cell phones.
Lee