Iconic and Epic Cards can be found in later sets starting from the highly popular Fabled set (Lorcana set number 9), Before that the highest pull can only be an Enchanted card.
Before most folks had even heard of building a 100-card singleton deck, WotC was producing multiplayer expansions for Magic in the form of Archenemy all the way back in 2010
You can even break the Singleton rule in Commander Draft
When I wrote the first iteration of this list back in February 2004, the latest set included was Mirrodin
A Cloud, Ex-SOLDIER Commander deck focuses heavily on Equipment, putting them on creatures to gain powerful, potentially game-ending effects
It cannot be easily splashed in two colors that aren't Blue and Green, and you cannot easily afford it in more colors like a five-color Commander deck