Not sure if anyone has mentioned this up until now, but a look on archive.org shows that some of these pages have existed since March 2005.
There are two important differences between now and then:
1. Then, all the text was black-on-black, so it would influence Google but be invisible to someone reading the page, unless he highlighted it to read it
2. The stories used then were much more benign. Some are stupid, but there aren't any celebrating addiction or suggesting gambling is a miracle cure.
Some examples:
http://web.archive.org/web/200503161...no-numbers.php
"When hunting for love at a keno game, remember that it is not enough to simply look at a potential sweetheart's keno card. You must understand the significance of the numbers they choose. Sit next to your target and tell him or her that this is your first time playing keno. Ask what strategy they used to select each number on their keno card."
http://web.archive.org/web/200503161...te-playing.php
"I was working hard yesterday to finish a report when I looked over at my buddy who was staring intensely at his computer so I messaged him - "John, what are you working on?" A reply popped up on my screen moments later. "Online roulette" it read. Online roulette - huh. And I thought that he was working hard so I wrote him again "you're playing online roulette when you should be working!" He replied "online roulette is more fun." I wrote back "how is online roulette different to casino roulette?" A minute later came the reply, "I can play online roulette from the office!" And then I got another message from him, "Also, with online roulette I don't have to push people to get my chips on the numbers I want. And online roulette is faster because I use my mouse to put bets on."
Plenty more here:
http://web.archive.org/web/200501010.../allslots.com*
So it would appear that this is a long-standing trick, but it suddenly got much, much worse recently - they stopped hiding the text, and they rolled out hundreds (thousands?) of new pages on much more malignant topics.
I can actually believe it was a disgruntled employee (or ex-employee) who flipped the switch recently to turn the entire catalogue on at once. But clearly it must have taken a very long time to write it all in the first place, so one must assume there was management approval at some point, even if there wasn't approval for the actual publishing of it. But this is all just conjecture.