Hm. Seems plausible.
1) The board has +buy/gainers (Margrave, Horn of Plenty, Black Market)
2) It has attacks (Margrave, Mountebank), so that once the engine starts hitting you every turn, it's brutal.
3) It has villages (Bazaar) and card draw (Margrave, Alchemist, Envoy).
It has all the components of a super-brutal awesome engine.
I mean, yeah, they're all too expensive. Alchemist, MArgrave, Bazaar, Mountebank... too many expensive things. But the potential engine there is downright frightening. I think it's not too surprising that once it got going, it was super. Just that it was too slow to get going - you had four provinces and three duchies by the time he started greening.