You are misunderstanding. Ofc everyone does it, you'd be stupid not to. But it is most definitely not allowed, as it is illegal to download papers from there. Nobody ever gets busted, but its bull to put that on a list of things you are allowed to do.

I think you're taking the title too literally. The article is about things you can do, but that you probably didn't ever consider as options. Replace "allowed to" with "can" in the title, and you'll get closer to the real point of the article.