Are you sure about that? There's a lot of slop on the internet. Imagine I ask you to predict the next token after reading an excerpt from a blog on tortoises. Would you have predicted that it's part of an ad for boner pills? Probably not.

That's not even the worst scenario. There are plenty of websites that are nearly meaningless. Could you predict the next token on a website whose server is returning information that has been encoded incorrectly?