I'm not a lawyer and I doubt it would be that big of an issue for some random blogger who can barely cover hosting costs with advertising revenue, but I remember there being some regulations (FTC rules?) regarding the separation of advertising and content.
For example if I recall correctly... you can be sued and heavily fined for conflating the two and not explicitly delineating the different types of information. Hence why Facebook and Google advertising can be pretty easily blocked by figuring out the meaning of div labels. Of course to thwart ad blockers, these div labels usually are cycled through pseudo-random characters forcing a cat-and-mouse game in maintaining block lists, but the intent of separation has to be there.
This is similar to the surprising effects of regulation in news reporting that ultimately gives minority viewpoints ample screentime in the spirit of 'fair coverage against bias', leading to viewers' false perception of systemic disunity.
The perverse incentives for mixing in deceptive ads or product recommendations is still there so people find rather interesting ways to sidestep the rules: e.g. hyping up stocks or spreading FUD either 'anonymously' or through intent-obfuscated 'press releases'. But then again these shady counterings are also regulated in other ad-hoc ways such as securities fraud law, fiduciary duty to shareholders, compensated spokesperson laws, libel laws, etc.