Issue is it creates a thunderous sub bass (like an out of control sub in a speaker system) that muddies up the bass in many songs.
Only if the IEMs in question don't fare well in regards to boosted bass. If they do, they won't spray whole midrange with THD, alas it'll all be clean & tight. Common misconception.
The top selling beers in the world are:
#1 Snow
#2 Budweiser
#3 Tsing Tao
#4 Bud Light
#5 Skol
Ergo, a beer made the "right way" should taste like those pale lagers.
Now, someone will point out that beers are not reproducers, and rightly so. But it's illustrative of the dangers of equating "what sells best" with "what is right."
Not quite. You'd have to make a blind testing w/ 20 different kraft styles & popular beers and assess how much each of them are liked, and then choose the ones that have least std-dev from the profile each way. Harman was computed that way. Besides that, headphones used w/ preference testng were LCD-2s and different "end-games", the results showed that it doesn't matter. One of famous beer vloggers in Poland made a tasting video while suffering from COVID-19 (note: he mentioned that drinking while being sick is dangerous), when having problems with smell. What occured is that he had problems differing between stouts, lagers and IPAs, all of which are incredibly different, but when lacking smell it doesn't actually matter. The difference is mostly in expectance.
How pretentious to call anything popular bollocks. Prefering flat response on headphones or on speakers is not some sign of higher intelligence, it's just a matter of different perception, but I'd stray from saying that it's somehow better - there's simply no real reason to do so.
The pop music with really deep bass that has deep market penetration at the moment has absurdly exaggerated bass. On purpose.
But... pop music is produced in a way that'll have most presence in the mid/upper bass region, simply because most people don't own anything that goes under 40-50Hz or that is all unhearable (e.g. in cars)...
Guys, I'm not trying to be smart, but we're delving very, very close to straw man realms... I think it's better that we stop and try to concentrate on facts. The fact is that flat bass response is not something that happens in rooms. Just like Toole showed that people in general prefer flattest speakers in blind testing, we can estimate that the same is true for headphones. In fact, that was the reason why Harman worked on blind-testing rig for headphones.