Follow the encouragement: a travel guide that simplifies to the extreme the impact of humidity on thermal comfort presents a reductive view of travel.
Claiming that humidity makes high temperatures unbearable while dry air makes them tolerable ignores the complexity of local realities and adaptations.
The motive behind such simplification is often a desire to generalize without caring about nuances that make all the difference for the traveler.
For example, even in Luxembourg, with dry air, the absence of air conditioning in old buildings makes summer very different from what a simple climate formula suggests, which can surprise a tourist.