This is a general principal of the world. Almost everything, including customers, getting dates, and wealth follow the same pattern: Pareto.
There's even a Bible verse:
Whoever has will be given more, and they will have an abundance. Whoever does not have, even what they have will be taken from them.
Matthew 13:12
May be more interesting to compare the jobs allowing open source contributions at the top of the scale.
Or put another way: comments closer to the top attract more karma than those at the bottom.