Maybe not when you were in school. But these days, yes. Yes you do have to give the details how you found any given fact that's not considered common knowledge
or established fact like George Washington was the first president of the United States.
In school, one has to cite ones sources. In math, one has to show ones work.
Outside of school? You don't have to cite the source of your fact. If you want to add gravity to your debate points here in a2k or elsewhere, you too will cite any relevant source in order to give weight to what you're saying. Especially if what you're saying is controversial or has its doubters waiting to pounce on what you say or write.