That’s for the courts to decide. It’s difficult to escape modern life though. Also, banning ads completely is a near impossible task IMO. It would be like banning messaging. Nailing down the definition of an ad would always lead to people finding ways around that.
“An ad is a message aiming to sell a product or service” --> define selling, define product, define service. Once those are defined then there’ll be a way around that too. “I’m not aiming to sell a product or service, I’m just informing the public that it exists”. Where would you go from there? You can’t make the act of informing a person of a product’s existence a crime: “Hey bro, I bought this new product and -” “OMG, you’re such a criminal for telling me about a product”.