Even back then, playing a card like Oblivion Ring was risky business, and Return to Dust was the favored card
Each of the Commander decks is built around a specific game, with four of the most popular ones being chosen (VI, VII, X, and XIV)
Mill decks will definitely be including this Jace Variant, as its ultimate ability is too tempting and hilariously mean to resist, and counter manipulation via Proliferate makes it that much easier to activate
While it's only a basic counterspell at its worst, this card's power comes from the ability to use it as a mana sink in the late game for both card advantage and copying your best creatures
Cheap datacenter proxies from no-name providers are one step above free
Oh, and I should leave mana up to counter any copies of spells I might've exiled as well, too