Question on grade weights / set composition

rose14com

I was reading an older thread discussing if PSA ever changes the grade weights for some cards, and that lead me to check out the Yaz master set (for my buddy) and compare it to the Rose master. I had been on a quest to obtain a 69 4in1 of Rose, and I did, and had noticed that card carries a pretty substantial grade weight in the Rose master (someday I have dreams of getting all my Rose's graded). However, the 69 4in1 of Yaz only carries a 2, the same as a 69 Deckle or 69 Decal. If the grade weight is supposed to reflect the difficulty/scarcity/value of a card, how in the heck can a 69 4in1 with Yaz be weighted the same as those 2 cards? I don't know my prices, but just gauging on what I paid for a Rose, I'm guessing a Yaz would be pretty damn close, and I'm quite sure you could buy 10-20 of Yaz's 69 Decals for the same price. Any ideas, I'm just curious.