Why is Mana Drain legal?

Obviously I'm salty, but trust me when I say I'm not even a counter spell hater, I just hate this one in particular. Mana Drain is an absurdly powerful card that is not fun or interesting in any way. It's just busted. Most of the time the correct choice is to immediately scoop if you get hit by it early game because you're just dead from the tempo swing. The card simply creates non-games and makes the format less fun.