No, I am not "conflating creation with publishing/marketing." I am making the point that creating work of any consequence is a time and cash intensive prospect, and that absent the IP protections that gave artists access to financial support outside the patronage system, the elites of pretty much every civilization since ancient Sumer have used their economic power to sharply control who does and doesn't work, and what does and doesn't get produced.
The absence of work from the historical record cannot be explained solely by the dearth of preservation or advertisement on the part of elites. It's also a product of active suppression by the elites of anything that may challenge - or even lead to a challenge - of their power and authority.
The best way to ensure that stuff like this never saw the light of day was to take full control of the means of production. This meant limiting access to both the tools of production and the training needed to use them well.
As far as our recent liberation goes, IP laws that allow creatives to finance their own production are only part of the picture. Other important innovations include the concept of human rights, the idea that freedom of expression is one of them, and legal systems that respect and protect those who engage in free expression.
None of this suggests that the desire to create freely and independently isn't a deeply felt part of the human condition. The point I'm making is that, until very recently, most people suffered under overbearing systems of governance that went out of their way to ensure that this creative desire was carefully controlled in the few cases where it wasn't brutally suppressed.
Saying the patronage system "worked" is a bit like justifying slavery on the grounds that mansions in the Antebellum South were remarkably beautiful, or that imposing the miserable conditions endured by peasants in pre-Revolution France was "redeemed" by the glories of Versailles.
It's possible to appreciate the artistic genius in work commissioned by monsters. But it's foolish to think that the mere existence of these transcendent efforts means we needn't worry about the conditions that produced them, or those who would allow these conditions to return.