I think that this spreadsheet is communicating several things well but I share it as a "reasonable bad case back of the envelope calculation". And if we mean the same article, it actually does a reasonable job at outlining the uncertainties around testing and national differences, and focuses on what is probably the most robustly comparable data point we have: Number of confirmed deaths.
The problem with models used by experts is that they are diverse hard to parameterize and that the scientific conclusions drawn are based on many different models not on one.
Exactly why replacing by something simplistic doesn't fly. I'll go on a limb and say if I tried something similar in this guy's field, I would be destroyed for publishing it. And rightly so.
The post in question mostly presents observations about the base line models and data taken from reputable and cited sources. It didn't make up simplistic models on the fly. I would say it is breathless journalism.
I also would wish for better explanations from the scientists actively working on it. My first go to is RKI.
The problem with models used by experts is that they are diverse hard to parameterize and that the scientific conclusions drawn are based on many different models not on one.
It's a very fluid situation.