as long as the content is valuable, it really does not matter who the original author is

It really does. I tackled also this topic about three months ago and I went even further and talked about "grey plagiarism" which is not copy pasting someones work, but rewriting it without even quoting a reference. This type of posts I saw even at people with close to 70 rep and really felt like shit when I knew I spent hours a day writing about different topics and would only get 0.20 or so per post.
In the case of news types of posts I agree that the only thing I could do is to gather info from other people's articles write the post in my own way, add personal opinions, and of course link references at the bottom of the post and that's it.
However when one makes a "scientific post" with all sort of data presented in it without him being the researcher and he doesn't even link some references to the "real author" or collector of that data used in the post for me is just a grey plagiarist, no matter the rep, and I feel pity for such person.