Its filthy with ridiculous plays, many of which have the capacity to wipe more than just your own lands and permanents, making it a great counter to decks with a lot of ramp while maximising your own mana and enjoying the benefits of recursion and Landfall
Adding 20 cards to your deck seems like a massive drawback that would hamper the consistency of your deck yet Yorion got the ban hammer in several formats, and some Modern decks still tinker with 80 cards, even without the extra creature in their sideboard
What it is is incredibly hard to beat
The sideboard copy of Teferi, Time Raveler is sweet for when you really need that effect
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But token commanders often deploy token doublers like Mondrak, Glory Dominus and Parallel Lives to amass gigantic board states, so the ceilings quite high