Is coursework which is worth 20% of your final Alevel Grade important

So according to our History teacher the grades we get for our history coursework is not important as it is only worth 20%. Does that 20% have the ability to help a great deal. The history teacher is leaving sixth form soon and everyone believes that he sent off coursework with low grades because he is leaving and it wont affect him and he simply doesn't have much care. Despite the fact that last year he refused to send off a single piece of coursework lower than a B grade. He said that the majority of peoples grades were at grade C and only 2 people in a class of 30 got an A. Is the 20% much help in the end