McDonald's hasn't revealed how many cards they're actually set to distribute
With combo decks like Dragon Link or Virtual World, you sometimes see those decks summoning 7 monsters per turn
Not to mention Dragons as a tribe are always desirable in Commander since you have various five-color options available in the format
(Though Ozai, the Phoenix King does this even better, allowing you to keep the excess mana.) Miirym, Sentinel Wyrm is solid, but only in green-blue-red dragon decks and nowhere else, so that's a tad limiting
There have been a few other Talismans along the way, including a few more recent colored ones that are starting to open up the design space for these artifacts
It's a supremely efficient 2-drop that helps you stay super aggressive