Of course web ad efficiency will drop if we stick to GDPR-compliant practices only. Perhaps reaching the target audience efficiently will become less accessible

Of course web ad efficiency will drop if we stick to GDPR-compliant practices only. Perhaps reaching the target audience efficiently will become less accessible to small businesses. Yet this is not enough to question if GDPR-compliant web advertising is possible. Okay, the number of TV channels is small, I get your point. But there also are physical ads, e.g. billboards, subway posters, cards/booklets, local newspapers which often are focused to a small number of physical locations but still happen to generate enough revenue to sustain a business. There also are agencies which would put your ad on posters all over the country - ad aggregator networks can still work and manage the consolidation this way, we only want to hide viewer personal details from them, not to eliminate them completely. This will decrease significantly (yet not kill completely) targeting efficiency, make display/click price bargaining more subjective but that's all.