Even simply put, if you are going to banish cards as a cost, it is more efficient to banish them from the Graveyard, where they are sent after being used as materials or costs, than to banish them from the field or from your hand
The catch here is that you can just float a ton of mana, resolve Upheaval, then use what mana you have left to deploy mana rocks and threats
After this card is Special Summoned, for the rest of this turn, other cards and their effects cannot be activated on the field, and other cards' effects on the field are negated
It doesn't matter whether you have 0 or less life, you're forced to draw a card while your library is empty, you have ten or more poison counters, you're at the end of your Nine Lives, your opponent is a Triskaidekaphile, and so on
Everyone is looking around trying to figure out where the destructive spell came from
Switch this Pokemon with your Active Pokemon