Fundamentally because we hold a 200 item array in memory as we stream over all hits, preserving the top 200 scoring hits. A standard view just streams all rows between a start and end point. The intent of a search is to typically to find the needle in a haystack, so you don't generally fetch thousands of results (compare with Google, who clicks through to page 500?). If you don't find what you want, you refine your search and look again.
There are cases when retrieving all matches makes sense (and we can stream this in the order we find them, so there's no RAM issue). That's a feature we can (and should) add, but it's not currently available.