The efficacy of advertising is sold primarily by advertisers. It’s possibly worth a vanishing fraction of what these ghouls say it’s worth. But so long as buying it and acting like a greedy invasive bastard is more profitable than ignoring it, even by a tiny margin, corporate giants will keep doing it, since the cost to them is a rounding error.
The industry enabling this is large because they get to sell the same garbage to so many bastards.