I think it's more likely that Urza causes Paradox to go than to go himself. Granted, neither will probably happen (nor should they).
We disagree on paradox engine
That card is a disaster that makes the game worse in its existence. If it goes infinite, it's a lame combo that takes away from the game's buildup, and if it doesn't go infinite, it makes turns long.
And on urza's fail state being worse than rofellos' fail state:
A two mana creature that you always have on turn 2 and always taps for its mana cost or more is way better than urza playing a random card from your library every turn.
To me, what differentiates this from Rofellos is Rofellos can let you cast a 6 mana spell on turn 3 if all you did was play lands and your general. Every game, turn 3 6-drop.
Urza will have fast starts, but not nearly the consistency of Rofellos.
Rofellos also requires you to actually have a 6-drop. Urza doesn't; 4 lands and your general lets you start freerolling the top of your deck with no other cards required.
True, but casting a random card from your library for 5 mana is not banworthy, nor is it even particularly strong.
The card as a whole is obviously strong, but that line of play isn't.
We disagree on paradox engine
That card is a disaster that makes the game worse in its existence. If it goes infinite, it's a lame combo that takes away from the game's buildup, and if it doesn't go infinite, it makes turns long.
And on urza's fail state being worse than rofellos' fail state:
A two mana creature that you always have on turn 2 and always taps for its mana cost or more is way better than urza playing a random card from your library every turn.
True, but casting a random card from your library for 5 mana is not banworthy, nor is it even particularly strong.
The card as a whole is obviously strong, but that line of play isn't.
Does urza effortlessly generate enough mana every game to be considered a ban?
I'm leaning towards no, because he is a 4 mana card himself.