Once you reach the phase of the game where you can afford to do multiple things per turn, you need card draw to ensure you keep having things to do (Circle of Power, Fight On!, Travel the Overworld) or at least cards which can be used multiple times (flashback spells, Ring of the Lucii, Shambling Cieth, Relentless X-ATM092)
Many such cards like Entomb and Chrome Mox got their ticket to Arena through a Limited event, or Arena Anthology, or show up very infrequently like a Special Guest that earn a pre-ban so as to not shake up any pre-existing legality
Who Should Lead: Sauron or Saruman
Finally, were going to limit appearances on this list to only two cards from each set
Then return them to the battlefield under their owners control
Yes, that is also the main disadvantage to getting card advantage through drawing cards and yes, discard is also weakened by diminishing returns which card draw isn't, I am not comparing discard to card draw as a way towards card advantage, just stating the facts about cards in isolation