Your link estimates the Covid IFR in the USA to be about 0.6%, compared to e.g. 0.4% for China where the population skews younger or 0.8–1.1% for several European countries and Japan where the population skews older.
https://www.cdc.gov/library/covid19/images/november2020/1124...
I’m somewhat suspicious about the numbers for lower-income countries though. In Mexico for example Covid deaths have been grossly undercounted. These kind of high-level estimates are hard to do reliably when they are built on poor-quality low-level data.
I don’t know why you are pretending that “good medical care” (by which I mean, the average in a typical developed country with a well funded medical system that has not yet been completely overwhelmed; as compared to the “poor” level of care available in many developing countries or in places where hospitals are collapsing) is equivalent to “exceptional treatment”. I don’t know what you mean by “exceptional treatment”, but your link says nothing about it.
There have been a large number of estimates of IFR, and they consistently range from about 0.4% to about 1.5%, mostly toward the middle of that range. Judging by the best current science, the 0.5% number I used is probably a slight underestimate, but it is at at any rate in the right ballpark.
If you e.g. guess the actual number of deaths in absence of any countermeasures would be more like 10–20 million instead of the range I gave of 15–50 million, that seems plausible enough (though I stand by my estimate). It’s a counterfactual in any case, since in practice extreme countermeasures were adopted in many parts of the world.