I think the biggest purpose of the wiki is to increase the learning curve of new players, so that they can become a productive part of the game faster. I don't think learning the ins and outs of OOC mechanics should be considered gameplay. I'm all for letting others know how the game works. I am not in favor, of posting spoilers. I think the distinction is very clear.
If I walk into a deathtrap which is described in the previous room's description, that's part of the gameplay. If I write about it on the wiki, that's a spoiler. No one benefits if I warn others on the wiki, because the immortals are going to move the deathtrap and everyone is going to have to experience the new deathtrap all over again.
If I make an observation on how a skill works, I think that's public domain. For example, I know how to get the familiar I want to get. It's a simple OOC manipulation, which has been liberally discussed on Dio's. Using this information, I can customize my conjurer's familiar. If I use this information quietly then I have a distinct advantage (that I don't need) over a newbie. How did I come across this knowledge? Just being around, reading dios and searching logs. <-- That isn't gameplay. That's just random chance and being around a while. So, why not short circuit the process and make the information accessible to the people who need it most. Newbies?