That may be the case, but they allow plenty of broken cards to be printed; cards that end the game by sending the rules into an infinite loop,
I don't think you've actually played Magic in the last 15 years.
or cards that end up in nearly every deck for a given color.
That's not an indication of the game being broken.
I think the real reason Magic wins the card game race is simple momentum. When your choices are playing a new game that no one else is playing, or playing an established game with an enormous player base, there really isn't much of a decision to make.
When you're at the top, the top is there to lose. And yet there's currently a CCG boom, with Magic at the helm, well in progress. (Some may call it a bubble and I wouldn't immediately disagree.)