Create, publish and continuously revise a "FamilySearch Best Practices" document. Then periodically bring this to the attention of FamilySearch users (perhaps once a session). The document would recommend best practices for sourcing, reason statements, merges, etc.
I am just another 'lowly' User/Patron ...
Great suggested enhancement.
Just in passing ...
Due to the complexity, of "Family Tree", 'FamilySearch' ...
I humbly consider, that there are ALREADY, many "Best Practice" Documents, in (/throughout) 'FamilySearch'.
They can be found in, the likes of:
For Member of the Church ...
Just my thoughts
[ ie. Way TOO many to have just in ONE place ... ]
Again, great suggested enhancement.
I know, that this certainly does not exactly address your suggested enhancement; but, I hope, that this may provide, some additional, insight; and, perspective.