Marion, are you looking at information on the Harneds? Because I ran into those same scenarios in recent days on that line.The funny thing was that the website that was quoted has a disavowal of the accuracy of the information right on the front page.
It may be that people are confusing copyrights with plagiarism - they have nothing to do with each other. If you are quoting Hammurabi or Sun Tzu, you must attribute the quote, no matter how old the source.. They are not your words! This is not difficult - I learned it in 4th grade, when I wrote my first book report.
My opinion is that listing the book/article/website in Sources does not mean that you can skip the attribution. The Sources area shows where you got your information, not where you lifted the biography from.
As far as using an outside website for information: without sources that you can check and replicate, that website is no different from a family tree from Ancestry.com or Family Search - unreliable (I am sure that there are reliable, sourced trees on those sites; however, most of them contain a lot of wishful thinking and errors that have taken on a life of their own).