What is the Matthew Effect, and how has it created unfairness among athletes, particularly in Canadian youth hockey and European youth soccer leagues?

In context, the Matthew Effect specifically speaks to opportunity as a precursor for athletic success.

From the text:

It is those who are successful, in other words, who are most likely to be given the kinds of special opportunities that lead to further success. It’s the rich who get the biggest tax breaks. It’s the best students who get the best teaching and most attention. And it’s the biggest nine- and ten-year-olds who get the most coaching and practice.