I don't think that's true because there are plenty of unisex gears and having two races mean they have to do the work for both races to make sure they fit the gears. And even in gears that are different for each sex, once you have an idea on how to make one sex fits a particular type of gear, it's not all that different to make the other sex (which would be more similar than a separate race) fit a different type of gear.
