Why the word ‘so’ ruins an interview

It’s hard to imagine that a two-letter word can cause quite so much anger.
Its use has been described as a ‘linguistic epidemic’ and such has been the
recent level of anger from listeners of an influential radio news program
about it that the issue this week reached the leader page of
The Times.
The word in question here is, of course, the ubiquitous "so" at the start
of responses in media interviews.
This is not a new issue, but listener frustration appears to have reached
so