However, HackerNews itself serves as an advertising platform, but the marketing is generally pretty minimal: “Show HN: I made a thing that lets you encrypt and compress files twice as fast previously thought possible” Is wanting to share that work or idea so bad?
We don't need advertising for that.
In 1950s maybe, but in the age of review sites, consumer reviews, forums, product search engines, vlogs, etc we could just as well find anything without advertising.
We can have flat listings of products, attributes, etc, and products raise to the top by good reviews, positive word of mouth, etc (with payola and review tampering punishable with hefty fines). Any other kind of advertising would only serve to raise awareness of a product that doesn't deserve it against others that do.
Besides most products, including the tons of crappy foodstuff, fast fashion crap, snake oil cures, BS $100 dollar for a $10 dollar third world manufactured item, crappy stuff people don't need, etc., would be better off not existing -- not having awareness of them raised...
Can, but in practice it does not. It's a motte-and-bailey defense. To paraphrase Feynmann, advertising can inform customers about the existence of a product the way sex can produce children - it can, but it's not why anyone does it.