Find A Grave offers burial information, which is augmented at times by date of birth, date of death, full name of person, and relationships to others. The most important information from a Find A Grave profile, whether the other information is accurate or not, is the location of the deceased body. Just knowing the physical location of the body is valuable information for a genealogist. And so, yes, absolutely include Find A Grave profiles in the resources of Wikitree profiles. If there are weaknesses in the profile, such as a missing stone or photograph, or incorrect information on the grave marker, then state it in the biography of the Wikitree profile.
Also, before judging the accuracy of Find A Grave profiles, consider that not all Wikitree profiles are accurate, either.