An interesting article about Steam trading cards

Because the article was mainly talking about games selling because of cards (thus giving those game that had cards an unfair advantage because people were buying those games for profit). That's an entirely different thing to what's going on with Retrovirus. I think this quite sums up what was going on back then pretty well

That being said, there are plenty of upsides, and Steam Trading Cards have done a lot for the success of the game. "I've definitely found more people buying it since we've added Steam Cards," says Sternberg. "Our day-to-day sales jumped to roughly double, and maintained being double what they were before, ever since we got the cards."

That's not at all why the Retrovirus cards are expensive, the cards are, as I stated above, expensive because the game did not sell well, and did not generate a whole lot of cards. The bit about it getting cards late added to the lack of cards because fewer people generated cards "naturally". Thus even lower supply->higher prices. If things worked like the article writer was saying at the point where Retrovirus got cards then we would have seen a sharp increase in sales for Retrovirus, which in the long run would have resulted in lower card prices for the game.

The closest thing that remains relevant today would be cases like Temper Tantrum. A game that, when on sale, can net you a profit from card sales, and that people bought for that very reason.