Exactly. The current systems are very far from reducing your work to a prompt.
However, I'm sure the current state of these AI models isn't the end goal of those working on them. And therein lies the reason why they're continuously consuming more training data, including in this context, art scraped from social media sites like Instagram that artists have published there.
Most artists are concerned about what's to come, not what is here now. Even then, what is here now is already viable for commercial use, and is already being used as such (in ads, articles, illustration work). Somebody starting out from zero probably wouldn't bother looking at art as a job given the current state of the AI models and rate of progress, and many very talented artists (who are always developing) are probably concerned about being overtaken.
A commercial artist needs to publish their work online to get visibility. Of course that opens their work up to being plagiarised. They'd be open to plagiarism showing their work anywhere. Before, there was a natural defence to this, which entailed somebody being able to actually recreate the work to a similar or better standard (something that requires talent in its own way). Now the defensive barrier is much lower, and continually getting lower.
If somebody told me that writing a text prompt to paint a waterfall was as difficult as actually painting a waterfall, I'd think they're either delusional, or ignorant/spiteful towards creatives and their work/ability.
Some people come across very unsympathetic to those already affected by AI models. It will be interesting to see if these same people can cope in the same manner if/when AI models can replace years of their own learning and work, especially if it does so by training on their own work.
Others come across very naïve about where this is headed. Personally, I don't think we're heading for an AI driven utopia where nobody has to work and AI can do everything. More likely we're heading for many people losing their jobs, insufficient numbers of jobs to meet demand, and monopoly of power in the hand of even less people/organisations than today.