As a person with strong opinions this is totally new for me. I give feedback very often and I fear sometimes I'm too blunt. I apologize to everybody who may have been hurt by my feedback!
However, the most common reason to not give feedback people told me is that they don't have anything to say („I don't have anything to say!“). Let me state this very clear: this is not true! (Nearly) everybody thinks this. This leads to the phenomenon that authors and/or developer who don't write controversial stuff about mainstream bullshit don't get any feedback at all. It is a serious problem – how can one improve without feedback? Only (constructive) criticism and feedback lead to new insights and only new insights lead to improvement. You basically take someone's chance to improve. Of course this is a little bit overdrawn, but think about it – there is truth in it.
That doesn't mean that you should give feedback to everything you see. A „just went to the toilet“ tweet for example doesn't need any feedback at all. But on the other hand an article about tooling in the web developer scene deserves feedback for sure. Tobias told me, that he didn't get much feedback in relation to the read counter of this article.
Of course feedback doesn't mean you should praise the author. Praising is fine if you think the author deserves it, but this is not what I mean by feedback. Write an answer with your opinion about the article. Drop a comment or a mail telling the author why he or she is right or wrong in your eyes. Do it also if you like the article and especially if you don't like the article. We can only improve if and when we get feedback!
Oh, and one more thing: in the non-commercial world feedback has a second, very important role: it generates motivation. When an author or a developer gets feedback he recognises that people are interested in the stuff the author/developer does. And this creates much motivation to continue and improve which again leads to feedback. Tadaa, you just created a feedback loop! ;-)
So the next time you read an article, use a software or visit a website think about this. Feedback is important. Tell the people what you think – don't believe you have nothing to say!