if you actually were to try and engage in artistic expression you'd find out the whole process from conception to finishing your creation is something worth the time, and mistakes/accidents that often happen during it can bring new ideas to the surface. In that process you have the ultimate control over how good it turns out. Be it comically bad or a masterpiece there's a charm in how you have expressed your idea.

AI flattens all that to a button click and regurgitates what's already been made by somebody else, oftentimes creating something you've most likely already seen, somewhere, and won't remember for long.

Yeah, I am. Same way "prompt programming" isn't a thing

Correct, they are not artists.

AI just lowers the barrier required for people to be able to express what's in their mind

Yeah, there's nothing wrong with people being about to express themselves, but that's not necessarily art. With art the barriers are things like talent, creativity, and hard work. Lowering those barriers mostly creates rubbish. Typing 'Make a pic of an x fighting a y and make it look cool!' doesn't make anyone an artist.