[nojito]

It is true and has been verified from companies who conduct proper studies internally and choose to release it such as eBay.

There is also an academic researcher who regularly publishes as well.

https://pubsonline.informs.org/doi/abs/10.1287/mksc.2019.118...

and of course there's Tim Hwang.

https://www.fsgoriginals.com/books/subprime-attention-crisis

Internet ads do not work past simple location based targeting.

[dillondoyle]

There are plenty of examlpes on both sides.

I have routinely gotten over 100% immediate last-click roi from fb ads, for many clients.

I know for a fact many others have too. There are a ton of direct to consumer online-only products that easily measure this. Just make a page or item which you only use to advertise on FB. sales/spend. Game developers track this closely too.

[runarberg]

This is anecdotal evidence. Nobody is disputing those exists. However I think FB and Google owe their existence a little better evidence, such as A/B testing, control group studies and even experiments to actually demonstrate their effectiveness. Until we have those (and perhaps we do; I seriously know nothing of the existing literature) the anecdotal evidence we do have should be taken only as indicative of effect, not proof of effect. Anecdotal evidence come with a ton of bias.