One of the main aims of WikiTree, is to provide 'one' tree, with all profiles sourced (as much as possible).
It is an unfortunate fact that the internet is littered with people who like nothing better than to vandalise other peoples work. Spammers on forums being a prime example.
Being able to add profiles to the one tree database, requires a member to volunteer, and sign the honour code. Without this, we could soon find the database filled up with bogus people, ficticious characters, and all sorts of unsourced garbage. Sorting that lot out would really be a waste of time.