The responsiblity is on the author to communicate at a level appropriate for their audience. It's not on the browsers to encourage/discourage certain content.
> Those people can look at a dictionnary when they don't understand said word.
In fact, the browser can and does facilitate this very well. You can already just double click then right click and search on any word to get a definition, and I'm pretty sure there are dictionary extensions that make it even easier than having to go out to a search engine.