This is true, and why you should never expect them to be "fixed." Their purpose is not to accurately gauge voter sentiment, it is to make republicans less enthusiastic about voting, and democrats more enthusiastic. The only thing "broken" about this year's polls is that they failed to have the effect of discouraging Trump voters.
They also may have backfired in that Hillary supporters who were a bit on the lazy side thought, “Oh, she’s got it in the bag, I don’t need to go stand in line.”