Having reliable access to a 12/12 in the command zone opens up so much fun design space to brew around, letting us draw silly amounts of cards, ramp crazy amounts of lands, wipe out opposing boards of creatures, and obviously (over)kill our opponents in glorious dino dominance
If thats, say, Gladiolus Amicita from Final Fantasy, not only do you get a beefy Ben, but Gladiolus will let you search for another land to drop onto the table
Despite a few really good frogs, it's possible to turn other creatures you control into frogs with spells like Polymorphist's Jest and Arcane Adaptation, so even some of your creatures outside the tribe can generate value
Its worth noting that the card needs to trigger on at least two players to be worthwhile, since only two cards on a delayed trigger for five mana isnt a great deal