It's what you get when a pretty ingenious mind meets one beast of a brain.
A proxy is used when a collectible card game player does not own a card, and it would be impractical for such purposes to acquire the card
There were two fairly major problems with the way this change was implemented
When such moment comes, even if its someone elses turn, the trigger does go off
With so few cards that actually cost mana, you can also purpose-build a manabase specifically to cover those costs, even when they might have very demanding color requirements
Sooner or later, people will have access to their pre-pandemic hobbies, factories will be able to print without restriction, and fans will have no problem finding a new shiny Charizard in their hands.