This is incorrect. SO is polluted with "noob" questions and answers, which is why SO is so useless. Google and now even MSDN search results are also polluted with SO hits which are mostly just noise. If anything SO needs more strict moderation.
I completely disagree. I'm an experienced dev from C++ learning Android/Java dev. Literally 90% of what I need is on SO (the rest usually from mkyong), thanks to google some of the answers even bubble up to the search page so I dont even have to click on them. I would be much worse off without SO.
A lot of people on SO seem to be answering just for points, half the time, or more, they don't actually know what they are talking about all or have experience with what they are explaining; they have often literally just "researched" the question and now they condense a couple of sources into an answer. Without having a proper understanding of the subject.
SO is bad for the whole industry. And there is not much that is worse than a "developer" copying an answer off SO and putting it into a production code base, without even understanding the answer they just copied.