It does happen with regrettable frequency.
if you find that many of your ancestors profiles are inadequately sourced and perhaps have not been improved for a number of years there are a couple of options, adopt profiles that are orphaned and add sources as needed.
If they have a PM, most should be open profiles because of when the people were born, you can go ahead and edit them, add sources etc as needed.
If that becomes difficult as often happens with profiles of people who were born and died in Québec/New France ask the Québec, or Acadian project for help, I have found the team members very willing to help either by suggesting places to look for sources or finding sources.