That is only true because targeted ads are possible.
In a world where there is no targeted ads, companies still need to get clients and compete. The marketing budgets of companies would not miraculously go down if targeted ads ceased to exist, the money would just go to other means, and non targeted ads are a very good candidate (also they can be extremely hard to block as they can be served first party if needed)
> The marketing budgets of companies would not miraculously go down if targeted ads ceased to exist
If marketing returns drop, all other things being equal, budgets being cut is the natural consequence, because less spending will be possible before declining marginal returns result in negative net returns to further spending.
Yes. TV advertising is actually much more targeted than web advertising. (In the sense than TV advertisers know precisely their target audience and its response.)
The various annoying remarketing schemes are a tiny part of advertising technology and really only exist because of the well-meaning but poorly thought-out ideas about privacy on the web.
Most of the internet ads are direct response. As long as companies get back more than they spend they keep spending. So there is no set "budget". If direct response goes away there is not enough brand budget to buy all the ad impressions so the prices go down a lot.
In a world where there is no targeted ads, companies still need to get clients and compete. The marketing budgets of companies would not miraculously go down if targeted ads ceased to exist, the money would just go to other means, and non targeted ads are a very good candidate (also they can be extremely hard to block as they can be served first party if needed)