There is a critical flaw in your logic in the last statement. You are assuming that candidates with scores below 420 are lower quality. They could be just older.
Unfortunately, the ranking system is ageist and considers youth to be a very important factor. So by that logic, a 23-year-old with a Bachelor's degree and one year of work experience is deemed "more valuable" than a 40-year-old with a Masters or PhD and 15 years of work experience. Very strange but I am sure Canada has some very good reasons for seeking a younger, more fertile immigrant population
