His excadrill video mentioned it only being banned in gen 5. New threats have arisen, like the powerful pheramosa . Also, excadrill was too overpowered in the gen because permanent weather. Being able to have ×2 speed and immense attack the entire game unless it's weather was cancel was too strong. Also, they both fill other roles. Excadrill can be a spinner as well as a SR setter, while dracozot is generally preferred as a hustle pokemon. Although, dracozot is in uubl and not ou. It can't spam bolt beak, as ground types destroy it. Hustle as a late game miss does t hekp its numbers either. It's dragon type is normally not worth using as a better dragon type would be garchomp. Garchomp packs bulk, damage, and speed, along with the useful ability sand veil, as a miss can turn the game around.
Overall, I'd say excadrill is better. As for sand rushers, still excadrill, but if your using a sand team, consider garchomp.
Also I can post this as an answer if you want I got carried away :P