M193/20-inch M16A1 was the standard when the ACOG was introduced. It got Trijicon their intro to the US military and helped win them their initial M4-NSN SOPMOD contracts. The rest is history.

M16A2 and A4 with Green Tip got them their Marine Corps contract and Army RFI sales.

M4A1 with M855 got them their Big Army contract and supports Euro military contracts (HK416 countries/armies).

Mark 18 and IPSC/USPSA? Rounding error numbers. Does the potential market justify a whole new product line? TA01B meets your barrel and bullet weight variances, and Steiner, Vortex, and others are following their generic arcs.

How many are you proposing buying from them, OP? Maybe a half-dozen over your lifetime?