Advertisement obviously works. But the premise or mechanism is not as clean and simple as you laid out.

Marketing, whether they are external firms or internal teams, have their own incentives, just like anyone else.

But… Personally I like good marketing and I‘m drawn to services and products who do so.

For example tech and games sometimes do very good marketing by providing educational resources, transparency through blogs/vlogs etc.

Some products are focused on a high quality, sustainable niche, and they do very pronounced, sometimes humorous over the top ads.

I „mistrust“ marketing if it wants to sell cheap crap in a disingenuous way. But I‘m glad to see ads for interesting, quality products.