It's possible Lutri, the Spellchaser would have ended up fine in Commander as it's ability isn't particularly game-breaking, but the format is known for its identity as a varied experience and having a card be ubiquitous and free for players to throw into their list was probably the deal breaker
You don't need a Squirtle and a Wartortle in order to send Radiant Blastoise onto the field, just as you don't need a Charmander or a Charmeleon for Charizard V
Mishra's Workshop created effects that in modern terms were even more obscene, letting you drop cards that cost six mana on turn two without spending any cards
That effect turns even modest attackers into serious threats and shortens the clock significantly
Once you know what youre selling, the next question is where to sell it
Shes an interesting one, because you can go deep on Faeries, or deep on casting in opponents turns right