There's also a significant difference here in that in your situation, you would have been providing the rewards and you would have had power to artificially manipulate the value of those rewards (make it harder to win your game without reward points. Here, the author doesn't provide the rewards he is simply stating what offers the credit card companies themselves are making.
At the end of the day, there is certainly still a moral hazard here but it is also a very different situation than the one you described.
It's not 100% obvious where that line lies, admittedly. I run a small side-project site (started as just something for friends/family) that lists checking and savings accounts that are free of "gotchas": free checking w/ no minimum balances, online savings accounts without weird caveats, etc. (http://www.pfstuff.com/checking/ and http://www.pfstuff.com/savings/, fwiw).
But, I also show some AdSense ads alongside some of the pages... which have the bad habit of advertising precisely the accounts that don't fit my criteria, and which I'm trying to steer people away from. Not always, but Google's algorithms rotate in such "bad choice" accounts more often than I'd like. I can ban some of the more egregious "10% guaranteed interest!" type stuff via AdSense's settings, but not everything. Perhaps I should just pull the ads entirely? That'd be the idealist thing to do, but of course would remove the (modest) monetization potential.