I think it makes that person fell like they are asking a stupid question when someone gives it a 1 star rating making the 1 star being the worst and 5 being the best.
Let's say that someone does a search on a topic....
A lot of threads come up. HOWEVER, some of the threads that have a lot of GOOD info in it are rated a five star. Because of this, the threads are more easily identified as posisibly having some good info/content. Saves some time for the end user...
By the way, I changed my mind and gave this thread ZERO stars!