Sufficient is not always complete, nor does it necessarily convey absolute denotation or connotation.
From Merriam-Webster online:
[3 : an occupation requiring knowledge or skill <the art of organ building>]
From the Online Etymology Dictionary:
[art (n.) 13c., "skill as a result of learning or practice," from Old French art (10c.), from Latin artem (nominative ars) "work of art; practical skill; a business, craft," from PIE *ar-ti- (cognates: Sanskrit rtih "manner, mode;" Greek arti "just," artios "complete, suitable," artizein "to prepare;" Latin artus "joint;" Armenian arnam "make;" German art "manner, mode"), from root *ar- "fit together, join" (see arm (n.1)).
In Middle English usually with a sense of "skill in scholarship and learning" (c.1300), especially in the seven sciences, or liberal arts.]
Language is imprecise, derivative, and changeful. This is one reason why these discussions have merit.