Lol that didn't take long. Honestly I read your post and thought for sure no one would say that. And then....
Too easy to exploit, as others have pointed out. If you aren't really an active player you can register so you will get card drops then just Need every time by never adding it to your deck and watch the MGP roll in when others are completely locked out.
Which is why I made an edit on the first post, and said something about it on the 4th page. It would change things to a possible quest based system so that way people would be able to get the cards, not have to fight with RNG being unfavorable, and that way people could do whatever they wanted with the cards. And I made that edit because people kept pointing out the same things like you're doing.
It's an evil system, but it's there to get people to do said content more than they normally would. Now I think there is a way to exploit ones vanity with these cards but I don't think people are going to like it. Foil Cards. Let's say you can only Need the card on a weekly basis and greed the rest of the week. However the cards which drop in this manner now have an RNG chance of being a foil/shiney card when used. You would have a group of people who do said content, fight over the weekly need, and then attempt to greed the rest of the week if they really wanted the "rare version" of the card while not affecting it's purpose in being there. To get people to do the content more than they would.
That can be achieved with several systems, tho'.
If you have a 10% chance to get an item or you have to get 10 completion tokens from that content, the average amount of runs to get it will be close to identical. RNG only adds a very minimal amount of extra runs on average because outliers are open ended.
Likewise, having a 10% chance for an item to drop and having 4 people roll on it is roughly equivalent to a 2,5% chance for the item to just drop into your inventory. Which is equivalent to needing 40 completion tokens. On average of course.
You can freely convert between personalized loot systems, open loot systems and token systems without compromising the function of the loot - to make you re-run content. RNG systems in general have the advantage that they allow for instant gratification despite high average run numbers (and thus, function like a cross-subsidy from unlucky players to lucky players). Token systems equalize the amount of runs and don't allow for instant gratification.
Just roll Need on it if you want it, oh my god.
So, this is apparently implemented now in a way? My boyfriend tried to roll on the card, which they had in their inventory and already claimed, and they couldn't roll on it.
So it looks like people can only get 2 at most now when they go into dun Scaith~
Just have it drop from the boss randomly upon completion. It's weird how it behaves this way for Void Ark and every other 24-man before it, but everyone has to roll for the card in Weeping City and Dun Scaith.