The artists who are that good are at that level because they work their asses off. They study and paint at a rapid pace, far more than others. Illustration for me is certainly a skill that you can improve on the more you do, and I'd like to believe this applies to anything else. 10,000 of practice to become a master in your profession. This quote that's overused makes a lot of sense. I say this for people getting into the business or simply fans of these artists. It's a backhanded compliment. You don't have to take my word for it, you just have to take my word when I say that I've heard and read interviews of people far better than I state this.
Doesn't matter how good you are, everyone needs to work their ass off to succeed.
I'm not saying talent is irrelevant. There are freaks out there that have incredible talent. Tesla, Beethoven, Shakespeare, Musk are all freaks of nature when it comes to their fields. But you can bet that they've worked their asses and engross their lives into their field. Look at Romario or Ronaldinho for Brazil, incredible talents that could have been much better if they had a better work ethic despite being freaks of nature when it comes to football. Now look at Cristiano Ronaldo, whose won every title for two of the biggest clubs in the world. He doesn't drink and is the first in training and works his ass off given by many interviews of football players who have played with him. What's my point? That even talented people need to work their asses off.