When adding a person to FamilySearch (or updating the record of a person already in FamilySearch), for many years I have been entering a detailed description of the source(s) used in the "Reason This Information Is Correct" box of the person's Name, Birth, Christening, Death, Burial and Marriage sections of the record. Yet, each of those sections are still showing "0 Sources". I suggest that it should show "0 Attached Sources", so that the viewer can see there is a detailed source description in the "Reason This Information Is Correct" box, but the source document has not yet been attached to the record. Too often, the "Reason This Information Is Correct" box is left empty.
If the conclusion has not been tagged to anything on the profile's Sources tab, then "0 Sources" is, in my interpretation, factually correct, regardless of the contents of the reason box. This is because a reason is not a source. A reason is the steps you need to take to get from the source(s) to the conclusion. If the only step needed is to copy the information, then there's no point to filling out that box. Attaching the source citation is a much better use of your time and effort.1