I have to imagine it's because they're not very popular. AB has had them for quite a few years and they're probably a pretty small and bespoke part of the market. I think there's potential in increasing sound performance in applications like Broad River Tactical SD Hub adapter, but so far in more conventional designs like AB Raptors the gains seem pretty conservative compared to what manufacturers seem to be able to achieve with advancements in baffle design. And while moving some weight further back is better than forward, the reflex modules are still just additional weight. And then they of course restrict the guns they can be used on due to barrel thickness or complexity of mounts in the OPS Inc version.