Anyone can post anything on Youtube, and anyone can put anything on the internet almost wherever they want to, forums, blogs, news letters, etc. so why is it supprising that we find so many fake and misleading things online? I recently came across an article about a miracle fruit that cures cancer. Cures it. No Chemo, no meds, just this little fruit can cure cancer 98.999% effective! Then I do my research, and find that the picture they used for the fruit is realy dragon fruit and the name means sour grape in Vietnamese. the fruit does not exist and therefore does not cure cancer. Why are people like that allowed to write all their random stuff online without people checking on it and taking it down? The answer to the second part is simple, the internet is so big that the number of people and how close those people need to look to get the majority of fake gurus banned from their posts is way more costly than the effectivness would suggest it is worth.
the first part is a little harder to explain. When forums and such were made, people wanted everyone to have the freedom to share what they know with the rest of the world, unfortunately, with many useful people comes many more unuseful people. so as long as knowledgeabe people have the freedom to share their knowledge, so do ignorant people have the freedom to spew forth junk.