In the past, there has been a lot of duplication and WikiTree's goal is to have one profile per person. It is taking a lot of time (and research) for volunteers to go through and merge all these duplicates. The WikiTree team finally decided not to accept GEDCOM profiles over 300 years old. You can still add these ancestors manually. This way you can check each one for duplicates as you add them. You may be surprised. As Dan said, many of these ancestors may already be on the site.