If you could make a parametric component from any collection of Revit elements, there’d be no need to distinguish between groups and families.
Groups would have parameters. Exclude Elements From Group would be replaced by visibility parameters on the group elements. Edit Group would be replaced by an uprated Edit Family In-Place .
Families could be created simply by selecting the elements and hitting the ‘Create Family’ button.
You’d need to be able to add relationships and constraints after creating the solid geometry, which is the reverse of the usual family-creation process. That might need some better tools, but I’ll leave them for another post.