Is it possible that the projections themselves affected the outcome? If people saw that they had a comfortable lead, they wouldn't be as motivated to turnout.
Then the polling results might ironically be more accurate if people believed in them less.
Yes they can affect the outcome, but the opposite direction than you described. People who feel their candidate is doomed to lose don't turn out. People like to vote for a winner.
edit: To be clear, when polls overwhelmingly suggest a landslide, it suppresses votes from both sides. But a much higher proportion of the losing side will choose not to vote, thus inflating the gap.
Then the polling results might ironically be more accurate if people believed in them less.