I'll try give you a proper analogy.

DH sprints, CH is a marathon runner. At the start, stat points you put into DH give you more- he "runs faster". However, if you have a ton of stat points, CH will eventually overtake DH in the long run.

The mathematical reason for this is that CH follows a (to the best of our knowledge) quasi-quadratic function. DH is better approximated by a linear function. This means that for high values, CH will overtake DH in expected dps gain.
But just as quadratic functions grow faster for larger numbers, they also vanish faster so smaller ones- in the "smaller number region", DH wins. Atm we're in the smaller number region.
There will come a time where our gear has enough secondaries to hit the "breakpoint" where the expected CH dps return breaks even with DH. At that point, we'll start stacking crit.