And that's true. But her lead in 2016 is substantially larger than what she enjoyed eight years ago. By way of example. Here's how the polling looked in the Democratic primary in New Hampshire in 2008, via Real Clear Politics.
Clinton led, often by a wide margin. Her largest lead was just over 21 points. (The numbers above are the Real Clear Polling average, incidentally, not raw poll numbers.)
Iowa was much closer. In fact, Clinton often trailed other candidates, including former North Carolina senator John Edwards.
Her largest lead in Iowa was 7.2 points.
Now compare that to 2016 polling -- which is still early, but a poll taken today is only about 50 days before the start of the polls above.
Hillary Clinton was the front-runner in 2008, ahead of Edwards and Obama, until she wasn't. Clinton is the front-runner for 2016, as well, ahead of a healthy dose of empty space and then Vice President Joe Biden and Sen. Elizabeth "No, Really, I'm Not Running" Warren (D-Mass.). It's a whole different race.
However, that can change.