Comment by fatfingerd

I don't think their analysis about caffeine is correct and doesn't cite sources. I've seen a lower temperature for a longer time more often being ideal for maximizing caffeine vs other components in pubmed research on teas, I.e.:

https://pubmed.ncbi.nlm.nih.gov/21339166/

If one does a lower temperature for a longer time it is often also equivalent to boiling for a very short time a.f.a pathogens. I think the relative bitterness is probably higher for higher temperature brews after normalizing on caffeine.