I disagree with that, why would someone watch the analysis of the news, but not the news itself?
If you are so interested in news to watch Newsnight I can't imagine them skipping News at Ten.
Well, if you're interested enough in politics to watch Newsnight, why wouldn't you watch television's flagship political programme Question Time? Most people who watch Newsnight are the same people who listen to the Today programme and have kept up with the news throughout the day on TV and radio.
And in any case, all the important news has been on at ten o'clock. At half past ten you're onto the sport, the and finally and the regional news, the latter of which appeals to a totally different audience. It's not the same news at 10.30, it's international politics vs a cat up a tree.