People have been battling over top-posting and interleaved quoting for fifteen years, about the time Microsoft introduced their HTML email client that couldn't handle proper quoting without messing up the whole message, and subsequently introducing email to people who couldn't handle even trying to quote properly.

This is nothing new. Anyone who's used to BBS's, usenet, or any pre-Microsoft email will probably assume that interleaved quoting is the only way to properly reply to a message.