Advertising (Which appears to be defined in your broad doc as anything that gets your attention without asking for it first) is the worst way to get people to pay attention to things, except for all the other ways. The alternative to "advertising" is the rate of people discovering new things dropping to 1% of what it is now.
1% of products have natural virality and will be found on their own. The other 99% of products and services in existence, no matter the quality, needs to be promoted so people can find them and use them.
Say you make an app that helps plumbers do their job well. If every plumber used it, plumber productivity would go up 50%, making life easier for all. It cost you years of your time and lots of money to make this great app, and you need a lot of plumbers to buy it to afford to continue working on it.
There's a big plumber app on the market already, but yours is way better.
How do you get plumbers to hear about your product?
1) The press? Uninterested. Plumber magazines or sites? Very low traffic - no way to scale.
2) Call or knock on doors of every plumber near you? If everyone did this, the spam would be unreal. Also inefficient and not scalable.
3) Referrals? You get some, but most plumbers aren't chomping at the bit to help their competitors. And because you started with so few, referrals are a snails pace and by no means exponential.
4) Organic postings and SEO? The big plumber app is way ahead of you. And 100 other worse apps clog up the listings. No one sees your posts.
See the problem? Without ads, you can't grow many many categories of genuinely valuable products. Even if no one else is advertising, you can't really grow without them.
This is barely a hypothetical by the way. I've worked with a dozen companies with similar situations.
Here's a real life example:
I was just hired to scale marketing for a particular app. This app currently has over 100 real reviews online, averaging 4.9 stars out of 5. Retention is nuts - 98% of people who ever started using the product (which has a monthly fee) are still using it. The company is three years old.
Perfect to take off, right? But few industries are actually viral. We just doubled the number of new customers per month using FB ads in the first two months of scaling it out, and we'll scale much further over the next 3.
Anyone who works in start-up growth will tell you the same things I am.