Exploring with AI doesn’t lead to the same level of learning. They are doing the equivalent of paying to skip the level up of their character and going to the final boss with level 1 armor
I look at it more like speedrunning a level. You're skipping the parts of the level that take up the most time, some times using hacks. Is it universally as much fun as playing the game? No, just like using AI to prototype might get you to the same place, but without the experience of discovery and blockers along the way.
But there's still value in people exploring new spaces they find interesting, even if they do not meet your personal definition of pareto-optimal.