Look, none of these criticisms are novel or unknown in the industry and it's well known that measuring the exact impact of ads is impractical but we're not talking exact numbers here, just whether personalized ads are generally effective or not. This criticism effects how effective it is but not the fact that it's generally effective, unless you think all ads are doing is shifting sales forward in time (which doesn't really make sense to me).

I think this is more of an effect for things like search or ads on an e-commerce platform (somewhat ironically the contextual ads people here are advocating for are much more susceptible to this) but less so for a lot of the more random ads, especially for niche products.

Edit: For me they are obviously effective. I think the more interesting question is exactly what the return on ad spend generally is but that would take very specific data that I don't have access to.