Fifth Dawn was the third set in Mirrodin and was inexplicably focused on getting people to play all five colors. In the abstract, this is fine, but this was in a set full of artifacts that gave you advantages for running them. It would be like if Onslaught Block culminated in a set focused on super-powered spells instead of really good Tribal creatures…

Oh, wait.

Darksteel, the second set in Mirrodin block, is notorious for driving off more Magic players than any other set, even the Urza block. It contained high-power cards for Affinity that did not require finesse to win with. It was like UG Madness in that the best deck was cheap, easy to play and frustrating to metagame against.