When a company does a market research they go with what sells the most. In the USA there is no contest which sells the most and it is not first focal plane.
We have range finders now a days to tell us how far something is so no ranging reticle is necessary. When shooting at greater distances a scope with a smaller reticle covers up less of the target. For squeak shooting it is a benefit. For extremely long range gong or rock shooting first focal plane is okay.
Leica is in the money business. They choose to make optics to get money. When the market is large enough for FFP they will produce them.
