It's not about difficulty, it's about mastery. It takes thousands of hours of practice to be able to draw the perfect line. Even if drawing said perfect line took seconds.
A large part of mastery also goes beyond the technicalities of expressing, it's also about having a good eye for what is worth expressing and what is mundane/boring/etc.
But it basically boils down to: art [of all kinds] is tricky and takes a lot of practice.
The "what is worth expressing" is where creativity happens. Technique makes you a competent hack. It's not enough for originality. So it's misleading to think it's all art. Technique and originality are different skills. The best artists have lots of both, but they're not related skills.
Thank you for linking to that gallery! It's very eye-opening. I dutifully went through several pages, trying to find something non-boring, and it was indeed all boring (with the exception of Bruegel, who shouldn't be in there).
Interestingly, I feel the same way about many works on ArtStation [1]. The artists try to draw something "cool", like a fantasy creature, but end up with just a basic picture of a human with lots of greebles [2]. Lack of imagination is very obvious.
At the other end of the spectrum for me is something like Wayne Barlowe's "Wargate" [3], an image with a whole new visual language for what it's trying to say, or Paul Veer's pixel art for Nuclear Throne [4], with very simple technique but very imaginative character designs. Apologies if my taste is pedestrian :-)
Interesting litmus test indeed! Some were boring to me, some really interesting -- Monet's painting of a winter day on that page arrested me (and I didn't even identify it as Monet right away) because the way the light came down and reflected off the snow and the clouds was just... amazing. So few artists paint light well. And I noticed myself drawn over and over again to the featured paintings of Galien-Laloue. I like the light again. Bierstadt's paintings are always a little over-the-top but if you can get really close to an original the details are amazing and make you wonder about the time and the tiny people. The paintings of architecture do rather bore me.
My criterion for whether something is art is whether it changes how I see the world. I guess something like Wayne Barlowe's "Wargate" (referenced in a sibling post) doesn't change how I see the world. It's too far removed from my life. But the light in Monet's winter day...
Ok, I'll bite. I found these fascinating. You could live in every one of them, it feels like I'm transported to different times and places, wondering what these people are up to, what's going on, enjoying the sunshine / snow / rain / rough seas. In a word, interesting.
The divided opinions on this gallery are revealing. I can see why someone would find these works excruciatingly boring, in that they are all essentially photographs with no variety in artist's intent or 'method of art' for lack of a better term. But looking at them less abstractly, there is a rich variety of scenes depicted which are skilfully created enough to merit closer observation. I think the parent discovered a really useful litmus test for how someone approaches art.
A counter-argument would be that you don't need to have good handwriting to be an effective writer, and you don't need to have good draftsmanship to be an effective artist. "If you can walk, you can dance. If you can talk, you can sing".
See the highly popular /u/Shitty_Watercolour on Reddit or "Get Your War On" comics by Rees, David.
Practicing technique can be nice, but it can also hinder spontaneity and creativity.
The magical inspiration in art is something beyond technique. The way you practice that is to just live your life.
Lots of people hold themselves back from drawing, dancing, and singing because they are afraid of being judged for not having enough technical skill.
A large part of mastery also goes beyond the technicalities of expressing, it's also about having a good eye for what is worth expressing and what is mundane/boring/etc.
But it basically boils down to: art [of all kinds] is tricky and takes a lot of practice.