You ARE, however, allowed to decide what constitutes Art - and the determining factor for many comes down to conception and intent.

With the advent of creation by prompting, the conception and intent is abstracted away to a patron/artist interaction as opposed to the tool/artist synergy you contend. Providing only instruction and infrastructure as input means the appropriate analogy is something more akin to Medici/Michelangelo than Mass-Production-Silkscreening/Warhol.

You may not get to decide what someone else's creative journey looks like, but you are more than entitled to critique the extent of its creativity and artistic veracity.