The economical fallout would be extensive. Google's and Meta's business model (and that of many others) would basically disappear overnight. While I'm not a fan of either, and think there should be much stricter regulation for (very large) tech-companies, this would make financing of a lot of important products infeasible. But not just in tech. Think about product placement in movies or television, banners in big sporting events etc. Who'd pay for that? The state? With whose money?
Also, it would make entering markets much harder, if you're not a household name already. If I read your definition correctly, you couldn't even give a complimentary account for your SaaS product to a reviewer ("by way of other agreement") to enable them to test your software (and hopefully write favorably about it if they're convinced). This would definitely hurt consumers.
I think you should be allowed to try to change minds. If anything, we should outlaw the massive tracking effort involved in advertising.
[1]: What about a political party publishing a newspaper and paying their staff? Is that okay? I could construct more examples, and life is even messier. On the other hand, I have to admit, that the focus on the payment aspect makes this much more palatable to me.