Why Do The DoH Role Quests Require Gathering/ Buying Materials On MB Again?

[Styrmwyda]

But Crystarium/Studium Deliveries are NOT Custom Deliveries! So they didn't "change"! They merely turned the class quests into role quests in ShB, and kept them that way in EW.
EW has its own Custom Delivery, which is Ameliance. So you DO have a Custom Delivery that you can buy mats from a vendor.
As for Tribal Quests, the Lorporrits are on their way in 6.3... may be not immediately next week, but probably in 6.35.

I know they aren't Custom Deliveries. I was wondering why you have to gather/ buy from MB the materials when in Stormblood the class quests provided the materials for you. And since Crystarium/ Studium Deliveries are similar to Custom Deliveries in format, I was also wondering why they don't have a vendor providing the materials.