You can't think of a reason why you'd want a local copy of your mail? Do you have control over any of your data?
Do I have control over my data? I'm not sure I understand the question, but in this case the answer seems like a clear no, as my employer manages the email server.
That said, NNTP is so dead at this point, outside some active BBSes that offer NNTP access. Usenet definitely feels like a wasteland when I've looked around the past couple years.