Iterating to get the right output from a prompt- and waiting for the output to be generated - is not an instantaneous endeavor. How much improvement could someone see if they dedicated that time to drawing or writing practice instead?
Developing a "voice" is done, at least partially, via honing one's craft, as well as engaging with art made by other people and cultures. The former is antithetical to prompting, and the latter is actively being destroyed by AI.
I can't help but feel that this strange insistence by industry that AI be used to all but usurp art ultimately comes from a place of jealousy, and/or due to the fact that some intelligent-to-Americans-sounding British voice saying something like "we're operating at the intersection of art and technology..." at some TedX talk causes VCs to turn out their wallets.
No, it is because replacing art is easier than replacing other jobs, that is the only reason. If they could they would replace something way more lucrative to them, but as is replacing artists is the thing they can do so that is what they do.