My observations contributing to the frustration:
* Developers believe performance is speed. It isn’t. Performance is a difference in measure between two (or more) competing qualities, the performance gap measured in either duration or frequency.
* Developers will double down on the prior mistake by making anecdotal observations without any forms of measurement and will vehemently argue their position in the form of a logic based value proposition. Example: X must be fast because Y and Z appear fast.
* Developers will further hold their unmeasured position by isolating their observations from how things actually work. Software is a complex system of many instructions. Except for the most trivial of toy scripts nothing executes in isolation. For example developers follow the value proposition that a grain of sand is tiny and weighs little, so therefore does not contribute to the weight or size of the beach. An example is that developers will argue to the death using querySelectors to avoid walking the DOM but in Firefox DOM walking can be as fast as 250000x faster than querySelectorAll, which is indeed significant.
I suspect there exist a variety motives for why developers reason things in this way, but from the outside it looks like a house of cards based upon argument from ignorance fallacies outputting really slow software by really defensive people.