Many people already make purchasing decisions by looking at comprehensive tests from non-profit foundations (https://www.test.de/) or one of the public broadcasters' (https://www.ndr.de/fernsehen/sendungen/markt/index.html, https://www1.wdr.de/fernsehen/markt/index.html), and then do price comparisons with one of the many popular price comparison websites (https://www.idealo.de/, https://geizhals.de/, https://www.hardwareschotte.de/, https://www.preispiraten.de/).
If your product is good, it'll do well in the tests and the price comparison, and be bought.
You only need advertising if your product is actually bad and you instead want to convince people to pay for it because you want it associated with a certain image of your customers. But in that case, you're not selling a product, you're selling a status symbol, basically jewellery (e.g., Apple, the sneaker market, etc)
And the market of status symbols is harmful to society anyway, so if it gets destroyed as collateral damage of a potential ad ban, that'd be awesome.