There's going to be far more economic repercussions if ads are yanked out of the market. Believe it or not but they do drive a huge amount of small business growth.
Advertising is zero sum. It doesn't create value, it just redistributes it. And even worse it redistributes it through psychological manipulation. Modern advertising is an arms race of capital to rob the poor of their time and money through the most aggressive manipulation they can.
In the absence of abusive advertising people would not suddenly stop spending money. They might even be more inclined to seek out new experiences without a constant mental assault by the largest corporations with the deepest coffers to bury them in their ads. Regardless of the way it goes, advertising is absolutely a net deficit to a small business - they don't have the capital resources or scale to permeate culture the way large corporations can. And if they are expending their limited resources trying to participate in the rat race they are sacrificing value to their existing customers and shortchanging their own growth for what is effectively an extortion of participation - if everyone else is deluged in manipulation to rob them and you don't participate there will be no money left over once the wallet has been rung dry by as many emotional vectors as possible for them to find you.
Actually, no. I do marketing for a lot of SMBs and startups that offer tech and service solutions not offered by the incumbents. Without ads there's no way for them to get people access to their superior products.
In terms of utility, advertising is negative-sum, because it misleads people about solutions to their problems. An advertiser has an incentive to try to get you to buy their product regardless of whether it's actually a good solution to your problem. In fact, it seems like the less useful a product is, the more it needs to be advertised. I've never in my life seen an ad for bread, but I've seen lots of ads for scams, fad diet books, and breakfast candy (sometimes called "cereal").
The economy growing is not necessarily a good thing. For instance, the economy would get bigger if the government passed a law requiring everyone to buy mud pies — a mud pie industry would spring up, employ lots of people, and add to the country's GDP. But society wouldn't be better to live in for it, because mud pies are useless. Likewise, the economy would be smaller if people didn't constantly replace their clothes to keep up with the latest corporate-engineered fashion, or if they stopped buying books like Rich Guy's System for Making Guaranteed Free Money in Real Estate, but people would still be better off if they did.
In the absence of abusive advertising people would not suddenly stop spending money. They might even be more inclined to seek out new experiences without a constant mental assault by the largest corporations with the deepest coffers to bury them in their ads. Regardless of the way it goes, advertising is absolutely a net deficit to a small business - they don't have the capital resources or scale to permeate culture the way large corporations can. And if they are expending their limited resources trying to participate in the rat race they are sacrificing value to their existing customers and shortchanging their own growth for what is effectively an extortion of participation - if everyone else is deluged in manipulation to rob them and you don't participate there will be no money left over once the wallet has been rung dry by as many emotional vectors as possible for them to find you.