Because Arena is the new, expensive, and special child, and must be protected
Yugi's use of "Final Geas" to render Kaiba's use of "Monster Reborn" ineffective is a reference to how Yugi's countered Atem's final play by having "Gold Sarcophagus" negate the effect of "Monster Reborn" and stop the Special Summon of "Slifer the Sky Dragon"
Take Food, for example, it's been around for years, but it was only with the recent Lord of the Rings set that it became a viable Commander strategy. The current output also makes the pacing go faster
While those are one way that Wizards mitigates how variance impacts the game (and my personal favorite), other options have existed for much longer
It can create water from its tail to splash and play, often delighting trainers with its cheerful antics
Lower Text [When Attacking] [Once Per Turn] If you have 7 or fewer cards in your hand, Draw 1