My view is that finding and re-posting content is of little value, the only thing of value (to me) is my own opinion and who originally wrote it. As long as the link to the original content exists, and that the original writer is attributed for it, that is all that is required in my view. Granted, paraphrasing existing articles shouldn’t be considered in any shape or form journalism, but that’s another issue altogether.
A decent diatribe against this is linked below. You can also read Marco Arment’s thoughts on it (who as the creator of Instapaper, knows a thing or two about links) – http://www.marco.org/2012/03/12/not-a-curator. Whether bookmarking services like this are good for the advertising-based economy the Internet relies on to provide free services, is also, a matter for another day.