That being said, I took this approach at one of my previous jobs, a fairly well known enterprise software company in the Valley, and I got blackballed for being too negative. We were working on a project and there was simply no hope of it ever working. The technical lead on the project was over-arrogant and under-talented, and essentially built a system that wouldn't scale. I brought this up a bunch of times, and gave solutions on how to fix it, but they were all rejected by the technical lead. I was told by my manager that I was being too negative and was given a poor performance review, which really rattled me, so I gave up the "good fight". 9 months later, the project was canned because of scalability issues.
So this "Cult of Positive Attitude" really does exist, can be pervasive in a company to the point of being toxic, and sometimes the best solution is to just leave, which is what I ended up doing.