While they don’t always respond and they may not know any more about the family than you do, it still may be worth contacting individuals who have submitted/corrected entries on your family members on FamilySearch. You may make contact with others who share an interest in the same family as you. This may be helpful when you are “the only one” working on a family or you have had difficulty making contact with relatives.
You do not have to put your own tree on FamilySearch to use the trees or to contact the submitters–you can search all you want, but will have to make an account to contact some submitters. You do not have to make corrections or tree additions yourself. Not everyone responds, but I have connected with others who had a collateral interest in the family and this can be a good way to potentially obtain pictures or information that you do not have.
Yes ,the trees have errors and they are not perfect. I’m painfully aware of that. Yes, not everyone will contact you back. Responses reminding me of these two facts will be deleted and will not be posted as comments.
Some people allow you to see their actual email and others must be contacted through FamilySearch.