I have to say that I am a bit puzzled on this.
The edit you show appears to be a merge that was completed (Van der Merwe-3754 into Schalck-10), and of the profiles merged, it does not appear the data you show ever originated from a GEDCOM import (see here where the profile was created and then data imported from FamilySearch Family Tree LXQ2-W4H).
If this merge created any massive errors or changes to data, it could have easily been reverted to its previous status (using the restore data option), then worked on at leisure to clarify and document all of the information needed.
On the other hand, I know that pre-1700 imports via GEDCOM can potentially cause some issues, but this is where the Merge process needs to be carefully reviewed by the PM's involved. I think the better solution to totally disallowing members from importing data is to try and do a better job at educating them.
So the correct process in this instance should have been to create Unmerged Matches, cleaned up the profiles, then performed the merge - instead of jumping straight to merging.