You know, I completely disagree with the your first sentence. Of all cooking techniques, baking seems to me to be the most scientific. You must carefully control temperature and moisture in order to get a decent loaf. It's practically an exercise in chemical engineering once you start adding things like chemical leaveners.
I thought about addressing that, as there is a huge scientific component behind baking, and if you could control every variable perfectly, you would get exactly the result you wanted.
However, reality is there are wayyy more variables than what you can find in a recipe, even a good one. And that's to say nothing of the techniques of master bakers. Compare a what a master does and what they're able to write down or tell someone and it's an enormous gap. That's where the art is.
Many arts use science. But when people say "it's more an art than a science", they mean something like "the production cannot be reduced to a simple algorithm", typically because the space of outcomes is large, has many dimensions, and doesn't have clear success criteria.
Chemical engineering? Isn't mixing chemicals just chemistry?
Regardless, there is no standard for baking, each little extra bit of yeast, sugar, etc. you add in can make it an entirely different product. This gives it its own personal craft aspect, hence why it can be an art.
Those are different recipes, but I'm not sure that's where the "art" comes in.
The challenge of baking is that the components aren't very standardized. You won't get a consistently good result by robotically mixing 1000.0g flour with 7.00 g yeast and 650 mL distilled 35˚C water, and mixing for 400 seconds. The flour varies from bag to bag, even of the same brand. Yeast is alive and responds differently depending on the temperature and other conditions; sourdough cultures are even more finicky.
As a result, there's an "art" to knowing when to add more water/flour or deciding when the bread is ready to shape and bake. I would bet you could get this more under control in a commercial/industrial setting, where you've got proofing cabinets that control the ambient temp/humidity and other specialized equipment. At home though, you've more or less got to do it by feel.
Clay works must carefully control kiln temperature, baking time, glaze production/composition, cooling time, clay consistency, room humidity, drying time etc. to prevent a clay work from going wrong. This doesn't make sculpting a science- you still must shape your object, in any shape you desire, with your hands, and express based off structure and pattern and paint and color theory or lack of colors. The end creation is still a piece of art.
When it comes to baking, you are still shaping, structuring, patterning, coloring(or not coloring) your breads.
