Sure, they might be able to put them back into a players hand from the battlefield or turn them into Islands, but mono-blue card effects just didnt let you search your deck for them, let alone place them on the battlefield
The card distribution is skewed heavily toward rares and premium treatments, which makes for an unbalanced and very expensive draft experience
Alongside something that grants deathtouch, the 1/1 can destroy creatures at instant speed: Even without the combo, there are enough utility creatures in Commander and Premodern that at least one copy is practically a must have in Goblins decks
The Thief lets you draw then discard a card when one of your creatures deals damage to an opponent or you draw three with a full party
We can see on the card Noxious Assault that the alignment of the creature that infects a person can impact the course of the illness, but is it solely that or does the creatures own mana alignment influence things as well
The simple fact is that artifacts are used to flesh out the weaknesses of colors