I don't know if the group you are questioning is new or one that has been around for quite some time. Many years ago there was a site by the same name. It was made up of people who had books and other reference materials in their personal libraries. They volunteered to do searches within their material for others for free. Some would also search records in archives and courthouses near where they lived.
They were organized by area, county or state, and listed what they could do for others. They were identified by name and email address. If one found something they needed it was necessary to contact the individual offering the assistance directly. As far as I know they didn't solicit or send out information without first receiving a request from someone.
I personally used that site with great results several times.