Alan, I missed this question when it was posted. WikiTree does not delete profiles except in very unusual circumstances. And unlike other sites, all profiles are owned by everyone. We certainly have a number of unsourced or poorly sourced profiles, and what they need is to be sourced, not deleted. Anyone can source them; it is not just the responsibility of the profile manager.
Now, should the profile manager be sourcing them? Of course. I made the mistake of uploading a GEDCOM several years ago -- something I will never do again, because the garbage produced by that one GEDCOM is still all over WikiTree. Gradually I am going through those profiles and cleaning them up, adding sources, but it takes time. Sometimes someone else comes and cleans one of these profiles up, and I am grateful.
Where it proves impossible to find a source, we still don't delete the profile. We bring it in to the Disproven Existence Project, sever its relationships to other profiles so it is not part of anyone's family tree, and provide as much information as we can as to what it was part of and the efforts we made to find sourcing for it. So if you find profiles that just can't be sourced, Disproven Existence is a good destination for them -- see the Disproven Existence Notices on G2G. Before we put the label on, we give a week's notice as a challenge, and sometimes people have actually come up with sources! WikiTree is a collaborative effort, and G2G shows some of the collaboration at its best.
Jack Day