I think there are a few caveats to this.
1. Chromis seem to do really well with Anthias, and often school together. The larger group helps to dissipate some of the tension amongst the chromis so there is less fighting.
2. Buying chromis at the same time and all are around the same size helps. This way the largest one won't bully the smallest ones, though there is still a hierarchy.
3. Having a fish that the chromis deem as a predator works to keep the school tight and pre-occupied. A blue throat trigger is a perfect example of this. However, unless you find a really small one, it's going to be a tight fit in a 73 gallon tank.