Can you provide some pointers to that data (as the parent did for the contrary position)? Forgive me, but it seems you work in advertising, so I'm not sure if you're the most unbiased person to assert something like this without evidence.
But with many parts of digital, you can show certain pages of your website exclusively to those who have clicked on ads (ie. hide those pages from regular browsers).
In this way you can directly measure the direct effects of the advertising spend.
There are many businesses, including three that I own, that have grown as a sole consequence of social media advertising. We have not promoted these businesses in any other way (no SEO, no trade shows, nothing).
I'm not going to share my advertising accounts with you; I'm just going to ask you to trust that when I get my laptop out and show my results to my 'marketing skeptical' friends, they stop being skeptical.
Actual words, from one of these friends: "wow. That is like a money printing machine."
Consider for a second: how many advertisers that are actually succeeding are going to publicly call attention to their success? Would you?
The only hint is Facebook and Google's revenues. They go up, and I am one of the people who makes their revenues go up.
spoken like a true used car salesman
I'd like to be proven otherwise, so, here are my key points, which you didn't contend with:
-> It's possible to completely isolate the effect of advertising spend, thereby making the effectiveness (or not) measurable.
-> I pointed to growing revenues on Google/FB's platforms, two platforms which make isolated measurement feasible.
In terms of _externally_ verifiable facts, that's the best I'll be able to give you.
The rest, you (and others) have to take on a/ good faith b/ using basic logic, that I'm telling the truth.