When it comes down to it for me the two rockets actually fill different roles. Ghorn and other tracking low blast radius rockets are meant for single target damage, of course they are ok at mob clearing and that but they most certainly don't excel in that area. As for DB a non tracking large blast radius rocket it performs exceedingly well in mob clearing and of course it's ok on single target too but not as good as ghorn I couldn't believe when I started using hunger of Crota after using DB. I was using it like I was DB and it was very poor. Then on things like wizards I was like holy shit it's great. So basically just saying just cuz they're both rockets doesn't mean they fill the exact same role albeit similar ones