For example, in this question someone provides a Wikipedia article in their answer, which I also did on my own answer to another question. For my own answer, I knew 90% of the information off the top of my head, but because I needed to doublecheck some of the info, I posted the source that I doublechecked from as well. Tangentially related, when I answered this question for someone, I referenced the Steam Support page. Do we want to encourage questions on this site that can be answered by searching the relevant support/help sites?
Is there a general rule regarding sources and when you do or do not need to list them? For example, I know, as a gamer, for an answer to this question, I would probably want to see a source from Valve or the TF2 blog or something, so I knew the person wasn't pulling an answer out of thin air. I'm not quite sure what to do or if there is an official stance on this.