So regulators should just take their word for it and allow them to slide on compliance because they claim they would be showing more ads in some alternate reality if it weren't for targeting? That sounds like a loophole that would allow pretty much everyone to ignore GDPR completely, and I think you'd actually have to live in an alternate reality to consider that reasonable. The entire advertising industry would be exempt from GDPR.
By that logic, they could fill an entire site with ads, and claim that since those ads are targeted it's still a benefit to users, because if the ads weren't targeted they would have to make the site larger in order to fill it with even more ads. There's no limit to how far you could take that.