When I feel like I'm doing good work, I'm a lot more productive, and I care more about doing things right vs just getting them done. Obviously constructive criticism needs to happen -- the author isn't disputing that. In fact, she says "it's been tough to get useful feedback" because people care more about cutting the other person down than actually evaluating the work.

It's very easy to couch constructive criticism in a few words of sincere praise/recognition of their work, and it generally results in them doing better work in the future. In fact, they'll be much more likely to listen to your criticism if you haven't immediately put them on the defensive. Once either side gets at all defensive, it's extremely difficult to have any kind meaningful conversation. If you always say "this is crap", then you're literally asking them to defend themselves.

If you haven't already, I would recommend reading "How to Win Friends and Influence People" by Dale Carnegie.