Semantics, and personal taste, or preference.
I like other artists more than Picasso, so I would not rank him as the "greatest" of 20th. c. artists. Preference.
On my desk, there is a small "pot", made by one of my daughters, at about 8 or 9 years old. Not because of who made it, but due to its inherent qualities, it has a place of honor. In it sits an exquisitely crafted bronze Toad, about an inch square. Likewise, the hollow knot from an Upper Peninsula pine tree, that holds my fountain pens. Functionality aside, I consider them ART, sorry, art. Over my desk, there are some metal advertising signs, and though one features the work of Haddon Sundblom, who was an artist, these pieces are not art, just reproductions.
My wife, also in the arts, and I have filled our home with art, most of which was acquired reasonably. Value has never been a consideration; like, response, emotion are. Most has NOT been approved by the gods of ART, just us, and though others might see crap, well, that is just opinion. At one time Van Gogh was considered crap, as were many other, now "approved" artists. Opinion. ( Some of our crap has transcended into being ART. )
When art becomes ART, mounted on a lofty pedestal, available only to the "chosen ones", then we have lost our way. Art should be a part of the every day, as in Native American culture, though this certainly does not preclude either specialization or excellence.