That's a prediction, not the polls. The polls indicated about a 3-4% preference for Hillary at the national level. She ended up with a 1-2% preference, so the polls were at least as accurate as in the past (nationally at least).

The fact that CNN interpreted the data poorly doesn't mean the data was bad. FiveThirtyEight stated repeatedly that Clinton's lead was not insurmountable and the a typical polling error could easily flip it to Trump.