simply because those cards are that useful
Being an artifact, you can get value when you sacrifice Dubious Delicacy, perhaps by returning it to your hand and reusing it, turning it into a creature, or all sorts of other things
Artist Erion Makuo handles this well, delivering a Scene where each character looks fun and active on their own, and the composition holds together wonderfully as a whole
Being able to power out a turn four artifact that ramps, gains you life, grows your creatures, AND draws you cards is way too much
Going into the missions tab after defeating solo stories will also offer rewards
If you have two copies of Doubling Season, or a Mondrak, Glory Dominus and an Anointed Procession, for each token you create, you actually create a total of four after the effects resolve