Why can’t I just use keywords?

Keywords are great, if you know exactly what you are looking for. If you know that, you might as well use a standard search engine to do the job. They won’t let you capture the whole picture but just the specific thing you are looking for.

On the other hand, the Explore tool search allows for a broad investigation based on information, which is lost when using just keywords. E.g. any specific context, different types of vocabulary to the one of the user, answers in different fields of science, etc.