Only if the game is purchased directly on Steam. A developer can sell Steam keys on their own website and not have Valve take a cut of the price. I think the only rule is that you can’t sell the key cheaper than the price the developer has set on the Steam store.
Makes sense to me. Their games isn’t made for their community and player base anymore. It’s made for their shareholders and they don’t care about BlizzCon.
I should give this game a try.