Your logic is fatally flawed, because the best cards at each slot are not universally available.
What I am suggesting is that this is basically what people do within each class. Every top paladin deck runs
Shielded Minibot,
Muster for Battle, and
Piloted Shredder for example. Similarly, dragon priest is the best priest deck because it exploits the idea that dragon synergy will let it drop overly large minions at each mana slot. There's a reason a better Zombie Chow,
Wyrmrest Agent, and a 4 mana
Fen Creeper are staples of the deck. We see a similar phenomena in Warlock, Shaman, Mage, Hunter, Druid, and Rogue. The only exceptions to this rule are Freeze Mage and Control Warrior, which are highly specialized exceptions for a reason, which are also tier 2.
the deck that has the most efficient minions to drop on curve would be the one everyone played, assuming it was the most effective strategy.
This is what Hearthstone has become. The top 5 decks in Hearthstone for example, according to Tempostorm, right now are Secret Paladin, Midrange Paladin, Aggro Druid, Face Hunter, and Midrange Druid. This is not 100% agreed upon, but most professionals believe that paladin and druid make up tier 1 while everything else is tier 2 or worse.