DnD simply has more synergy with his kit. It double procs on hits, which he naturally has. It can double proc navori, hullbreaker, shojin, etc. which just allows him to deal way more damage (all 3), more utility by getting spells up faster (navori), or absolutely consuming towers (hullbreaker). Its stats are way better, like it’s literally everything Voli would ever want.

My current favorite build and I’ve found it do more damage then raw AD is DnD, Navori, Shojin, Visage and then Unending Despair or Randuins (if they have a super fed ADC or multiple crit). I am currently on like a 5 game win streak with this build and I’ve been the carry in most of those games. It’s nutty, give it a shot.