It's not more popular because of the author,
I met him back in the day he announced this stuff and he is hard to deal with, that is number one. He comes into this world from NASA and tries to tell you how to do your job vs understanding how we do our jobs. Then add on the things he focused on initially in the software, like the self-destruct feature, nobody cares. Finally, he is under the impressions this stuff is top secret and you're not authorized to know anything. Outside of the military he is super dismissive regardless of your background, and by that, I am not talking about me, I have seen him do it to others.
The standalone nature does not help...
I will say his software is no better than FFS or Coldbore, it's actually very similar and with Hornady embracing 4DOF it's on par with what Aim-e does, for free, in an app or online from Hornady. But he is right in the fact there are known errors in Point Mass and 3DOF (the software used in most apps like AB) and he took the time to address them. If his engine was available and put in an app, it would probably be very popular, but then re-read what I wrote, he probably believes you have no business using it as that is his attitude.
As a person, he is hard to work with, at least that is my take.