Parity in football is, by and large, an illusion — the product of small sample sizes & a single-elimination tournament. In the last two decades, the NBA has produced nine unique champions (vs 10 in the NHL, its closest analogue in terms of season length and playoff structure); free agency, in allowing for the free…

I am guessing that it is logic.

Yes, because the most popular sport (soccer) in the world does not have elite talent aggregation by the top teams in every league except MLS.