For companies doing this the right way, the banner was just the tip of the iceberg, loads of work went into ensuring compliance behind the scenes, so customer and employee data was not shared with 3rd parties unknowingly. In one case the list of 3rd parties went from +400 to about 70, this is in my opinion a win for privacy, the culture around sharing your data went from casual to cautious.
Secondly, the culture around trusting meta and google blindly with behaviour data changed drastically. Businesses became aware of how much valuable data they share with these platforms, which actually puts them at great risk, should you really give these platforms detailed data on what customers browse and buy on your site, so they can use the data to sell targeting for competitors, or direct users towards their own shopping platforms?
So, yes the law is not perfect, we all hate the banners, but at least what happened in those early implementation days when the banner became law, was a change in culture around how data was shared and a better understanding of the risk for the business of using 3rd parties.