Andrei Tarkovsky in his book Sculpting in Time argues that Avant-Garde is an incoherent term when applied to art. He says:
“The whole concept of avant-garde in art is meaningless. I can see what it means as applied to sport, for instance. But to apply it to art would be to accept the idea of progress in art; and though progress has an obvious place in technology -more perfect machines, capable of carrying out their functions better and more accurately- how can anyone be more advance in art?”
To impose a scale of maturation short changes the history of art, to say nothing of the arrogance. Art is not a race, nor is it a technology to be improved upon.
I would add since the Avant-Garde is a military term for the forces that probe the enemy and claim territory that to apply it to Art transforms it into the turgid business of war. The object of Art is shifted to claiming territory and killing the old guard.
To switch this term with Experimental Art does not help the matter. Tarkovsky goes on to argue that since Art is a living organism to experiment with it is “senseless and immoral”. Art cannot be experimental unless it be barbaric for one does not experiment with the living.