I would expect that he's technically correct in the way that one could say that many people do play those games with high-performance rigs but it depends on one's definition of "many". I personally believe that the overwhelming majority of people who play those games do so at a casual level as opposed to a competitive level.Do you have any examples for me? I'd like to check a few of your sources so I can learn a bit more about this testing.
I would also expect that most are youths and teenagers (especially Fortnite and PUBG players) for whom things like R7-3700X3D CPUs, RX 6800 XT cards and 120Hz displays aren't within their budgets (or the budgets of their parents either). That's why the Steam survey still shows a strong presence of the GTX 1060 and 60Hz displays. There's good, and then there's "good enough". Most of these "e-sports" titles don't require high-powered hardware to run very well.
I definitely agree with you, in my experience, I have never been able to tell the difference between "fast" RAM and "slow" RAM. I would expect that the biggest impacts to be had would be in productivity where massive amounts of computer resources are used for a single task, like Cinebench rendering for example.