N-gram: What I didn’t see

I’ve read that the engine does have a bias. I haven’t seen it personally due to my limited use of it but apparently there are a lot of scientific literature and large numbers of incorrectly dated and categorized texts. So due to these errors, its hard to use this tool to study language. The increase of scientific literature causes other terms to decline. So apparently the tool is not developed enough to keep things in perspective. Just because all this scientific literature is being uploaded doesn’t mean its the only material this time period is reading into. It also doesn’t list another other links besides books, magazines and newspapers. There are no blogs or social media links to refer to when the search engine gives links to the time periods for the phrases you look up. So I think its pretty limited in that sense. I don’t think theres anything to overcome this because not every piece of literature is possible to upload due to copyright issues and simply availability. Its also not an engine thats advertised much. This is the first time I’ve come across it myself.