That's a fair point, and I agree with both of your solutions: We should promote the availability of works from past eras, and encourage more new art from underrepresented cultures and groups. But I don't think there's any need to discourage or reduce the creation of new art overall. There seems to be a concern that truly beautiful works of art will get buried under a flood of disposable pop culture trash and forever lost in the glut. I'll admit there might be some truth to that, but for the most part, I think it's a greatly overblown fear. Shining jewels are bright enough to stand out on their own merits.
Also, I don't really want a world where all art is high art. There are times when I'm in the mood for low art, sometimes I just want to sit back and enjoy some shallow comedy or mindless action movie. I enjoy a good steak, but that doesn't mean I never want to eat hamburgers or cold cuts again.
Unless you consider variety to have its own value, which I do. I disagree with just about all of that post's fundamental premises.
I don't think society should discourage economic inefficiency, at least not beyond the inherent discouragement that comes with unprofitability; I agree that unprofitable activities shouldn't be actively subsidized, but I don't see why they should be actively suppressed either. If someone had a lot of money to burn and wanted to fund some vanity project with no real artistic value, or just decided to give money to writers and painters and filmmakers to do whatever they wanted even if it had no public appeal, I don't see anything wrong with that. And if instead of one independently wealthy sponsor, it was several thousand fans contributing $20-50 each for a studio to make a new season of the trashy show they liked, all the better.
And I certainly don't think that people would be meaningfully better off with a smaller variety of art to consume, even if it meant a higher proportion of better quality are. I consider plenitude of options to be a good thing in itself. Besides, quality is extremely subjective anyway, which means that at least some people would be left with less art that they personally consider enjoyable.
But the assertion that I find most objectionable is the idea that people waste too much time consuming art and media already. Let people do what they want.
Your post reminded me of this article, which touches on a lot of the same points, albeit with a bit more vitriol for a certain kind of anti-aesthetic libertarian: https://fee.org/articles/against-libertarian-brutalism/
Except the thrive/survive dichotomy applies to conservatives and liberals in the classical sense, not the economic right and the economic left. And by that standard, libertarians are firmly in the liberal category, even if their right-wing economic views are more commonly associated with conservatives in modern times. Even the rhetoric that right-libertarians use to justify their economic policies is distinctly different from - and in some ways, diametrically opposed to - the rhetoric that conservatives use to justify the same or similar policies. Conservatives tend to focus a lot more on scarcity and have a very survival-of-the-fittest interpretation of capitalism, whereas the libertarian view of capitalism is centered more around the idea that a rising tide lifts all ships. (To use a MtG color wheel analogy, conservatives have a Green/Black view of capitalism, while libertarians have a Blue/Red view of capitalism.) That's not to say that libertarians don't recognize the value of competition, or that conservatives don't care about economic growth and technological progress, but there's certainly a huge difference in emphasis there.
I think the real reason there's such a shortage of distinctly libertarian art is simply because libertarians are a fairly small group, and also fairly disorganized/decentralized, so they just don't have the cultural influence that left-liberals or conservatives do. Although it's also worth pointing out that a lot of mainstream media does have strong anti-authoritarian and individualist undertones that I would consider to be libertarian in nature, even if it wasn't specifically created for the sake of promoting libertarianism.
Most libertarians I know believe that a more 'right-wing' economic system will help the poor, along with everyone else. Libertarians generally don't tend to worry about "freeloaders" the way conservatives do, which is why they mostly focus on government regulations and corporate welfare, while conservatives mostly focus on social welfare. When libertarians do take a stand against social welfare, it tends to be less about freeloading and more about welfare programs creating perverse incentives (e.g. discouraging people who want to work but would lose their benefits and be worse off if they did). Just look at the difference between libertarian and conservative arguments against the minimum wage. Conservatives will go on about how uneducated burger flippers don't deserve $15, while libertarians will focus a lot more on the fact that increasing the minimum wage will just make it harder for people to find work and make poor people worse overall.
Libertarians largely fall on the 'thrive' side of the thrive/survive spectrum. They might be closer to the middle than the far-left redistributionists, but so are moderate center-left liberals. The only difference is, unlike the center-left crowd, they see government intervention as the main obstacle preventing people from thriving.