Jesus. This makes it reasonable to just buy $100 worth of your own game every month, just to make sure. Assuming that the number of real sales cover Valve’s percentage and then some. Yeah, that’s a non-zero opportunity cost for you, and additional float for Valve, however petty it may be. But for a small developer, maybe that makes sense.
It’s even easier than that. Both of these genres have design features that require minimal balancing, making for an even faster dev cycle.
Roguelikes side-step the need for traditional game balance by providing meta progression and building inevitable-death-by-impossible-odds into the core game. For Roguelikes that actually have an ending, all the developer needs to do is provide enough meta progression perks to overcome the game’s peak difficulty, for even the worst of players. Everyone else gets bragging rights for beating the game faster than that. Either way, the lack of balance and “fairness” in the core design are features, not flaws.
Deck builders follow in Magic The Gathering’s footsteps: you never need to fully balance it. Ever. The random draw mechanisms, combined with a deep inventory of resource and item/creature/action cards, make it unlikely that a player gets an overpowered hand all the time. Pepper a few ridiculously overpowered cards in there, and it just feels more fun. Plus, if you keep the gravy train going with regular add-ons, the lack of balance is even further masked by all the possible choices. And yes, some player will min/max a deck at great personal expense and wipe the floor with their opponents because it was never fair in the first place, and doing so is a feature.
Whoa, false scarcity, virtual goods tied to an online service, and nosebleed prices? What’s not to like?
Oh, it’s petty cash to be sure. If you have $100-ish bucks to throw around, you probably aren’t going to miss much by not doing this. Unless, of course, letting someone else take even one dollar from you in this way is against your religion or something (i.e. the principle of the thing). Conversely, if you need the handful of dollars this makes, you probably don’t have that kind of walking-around money in the first place.