I partly agree with you - I used to think of mechanical difficulty as a kind of 'proof of work' for art. Nowadays I am less interested in the idea of what counts as art or not.

However, consider works like photorealistic drawings of eyes (usually at a very large scale). A lot of people like these, and consider them to be fine art, while others (art critics?) consider them bland. Contrast that with a Picasso flamingo drawn with a single line.

There is artistic value in high-effort, low concept works as well as low-'effort', high-concept works and other combinations. Perhaps what we are all looking for is effort of some kind (I prefer human effort) whether that is conceptual effort or practice in drawing lines on paper.