The to do list sounds excellent for people who were skipped for a reason during the import. In the situation I'm thinking of, though, the children were not included in the file to be imported. The place holder was created by the GEDCOM export.
See the list of children on profile Baicom-294 for an example of what I did with those placeholders. Those are my maternal aunts and uncles, still living, who haven't decided whether they're willing to have a record on WikiTree.
The profiles created by my TMG GEDCOM import may contain placeholders if any child of that person was born after 1915 and they didn't have a death date in my TMG file. I didn't include them in my export but my TMG GEDCOM included placeholders for them. It's a clue that the WikiTree profile is missing for someone I know exists.