I would take those claims with a grain of salt, even it they were true, a bunch of workers in an assembly line cannot make a big statistical difference when hundreds of thousands of systems are being built and tested before being shipped for sale.
Also, I wouldn't give Amazon reviews much statistical value either, people who don't have issues with their products rarely ever post a review, my PS4 is working fine and I didn't waste my time posting a review for it, whereas consumers who get defective products vent their anger with negative reviews 90% of the time, such is human nature.
EDIT:
I bet over time most original systems failed, I had two 360s that died, one of them not even a year after purchase, and my fatty PS3 also gave the ghost after a few years, both the RROD and the YLOD killed a humongous percentage of all 360 and PS3 systems sold in the first year, too bad we'll never have an official number.
As for the Wii, you're probably right, I didn't hear of many cases where the system died, then again, most of them were collecting dust a year after people got them