All that's necessary is making it possible for people seeking out your type of product to find you. And for revolutionary products, there's word of mouth.
If anything I think capitalism would function better without ads, because I would argue that advertising overall results in less informed customers, especially the modern lifestyle/brand type of advertising that's clearly quite effective at manipulating people.
There are second order effects of ads that we’d need to consider. Facebook and Google wouldn’t exist as we know them. Maybe that means some of their research doesn’t happen?
By contrast in parts of the world with relatively negligible advertising, markets tend to be heavily decentralized.
And I think this makes far more sense of you think about it. If you make a soft drink that is rated far higher than Coke in blind testings, or perhaps one that is near indistinguishable in flavor, but cheaper, you stand very little chance of competing successfully. There's a reason Coke spends billions per year in advertising, and it has nothing to do with reaching the three remaining people who are not aware Coke exists.
And yeah without advertising the "free" services on the internet wouldn't exist, replaced by a mixture of genuinely free services, and for-pay. This would IMO be a dramatically better state of affairs. Businesses whose actual customer is not the people using their product/service leads to such dystopic nonsense.
Would it even be possible to safeguard the product reviews system from bribery? The current systems we use for product reviews obviously would be unsuitable.
At any rate, I commiserate about the role of branding and advertising today. It's as often noise as it is information.