The exact point is that the critics remain silent, while the believers (or those doing it on purpose) carry the false news forward. Then those posts will appear on the search engines. Then those searching about the topic will become convinced based on big number of similar posts.
Attempting to correct misinformation, for instance, here on Hacker News, is essentially impossible and pointless. This screw story, like many others ("MBP Retina is unrepairable", etc.) play into an ideology[1].
And no facts, no matter how well sourced, can defeat ideology when the ideologues have the down button and outnumber the critical thinker.
For instance, pointing out that Apple licensed the technology they got from Xerox back in the day, a stone cold and indisputable fact, gets down voted into invisibility and claims that it isn't true and that it was stolen, here on Hacker News. The claim that Apple stole from Xerox has been repeated so often and in so many cases that it has become "fact" in their minds. Another example is the idea that Apple didn't invent any new technology with the iPhone. They need this to be true, so they spread all kinds of nonsense (like 2001, a movie, is "prior art", which shows a significant lack of understanding of what patents are)... and they believe it.
It isn't simply that people are gullible, its that ideology (and apple hating is a prevalent ideology) is stronger than reality for so many people.
[1] Maybe religion is a better word, it feels more accurate, but is more likely to be taken as a pejorative so I'm going with ideology.
This sounds a bit like the problem of the proliferation of news on cable TV and on the Internet. With there being so many choices for news, people tend to migrate to the source that aligns with their preconceived notions. So instead of being presented with information that may run counter to what they believe to be the truth, they only get their views confirmed.
With so many sources available, it's difficult to correct misinformation. People tend to believe what they want the truth to be, and now they have sources to confirm it.
There is also a lot of (vocal) people that like to justify their consumer choice with moral argumentation. I guess when it comes to tech choice, tech minded people can't live with the fact that their reasons are mundane (like the screen better, better contract, or much worse the shape is better, your wife would like you to have the same one)
Apple also makes it hard for tech people. It is a consumer oriented brand, choosing them is like drinking a beer with your meal rather than carefully selecting the appropriate wine.
