I think the reason why "work hard" is such a common piece of advice is because it's really the only actionable piece of advice you can give. It's true that most, if not all, success is ultimately more attributable to luck than effort, but you can't do anything with that. People ask, "How do I be successful?" seeking some sort of miracle answer that they can actually implement in their life, but there is none. Even successful people don't have the answer to this, because no one can comprehend the full scope of their life, decisions, and circumstances to really identify, "This is how I got where I am today."
But no one wants to hear that when they ask how to succeed, they want to be told what to do. You can't do "Be lucky." You can't do "Come from a wealthy and supportive home environment." But you can do "Work harder." It's less a formula for success and more of a coping mechanism for maintaining the illusion of control in one's life.
And "work smarter, not harder" isn't necessarily actionable advice either - it's tantamount to saying "Come up with a good idea." Well, if you were able to do that, you probably would have already, wouldn't you? Hell, maybe you already have but you just haven't seen the fruits of your idea take shape to prove you did, in fact, know what you were doing.
The way I see it, success in a field like art is essentially the same as winning the jackpot. Odds are slim and there's no such thing as a tried and true strategy, but your odds are reduced to zero if you don't play at all. So continuing to work is the same as continuing to play. And your ability to continue working is the same as still having enough money to make bets.