I note yours
so I understand your position, but I'm going to spin the whole thing anyway.
(what I write below is probably not news to you)
Far-fetched and improbable:
Purely theoretically, if you have a listening room where you with speakers that have anechoic flat FR but in your listening room, because of:
Room modes are the collection of resonances that exist in a room when the room is excited by an acoustic source such as a loudspeaker. Most rooms have their fundamental resonances in the 20 Hz to 200 Hz region, each frequency being related to one or more of the room's dimensions or a divisor thereof. These resonances affect the low-frequency low-mid-frequency response of a sound system in the room and are one of the biggest obstacles to accurate sound reproduction.
en.wikipedia.org
..that gives you to some valley or peak of 10-15 dB compared to speakers that anechoic have an opposite valley or peak so then in your listening room that will take out what your room acoustically creates. Then these non-flat anechoic speakers can sound better for you.
BUT, that is theoretically. There are many ifs and buts in the whole thing. You should know how your listening room works, how it works with the speakers placed in X location. Plus you have to find speakers that have this crazy FR. Practically impossible I would say. Which shows that no manufacturer creates speakers with custom crazy, cranky FR just to fit in a specific room.
There are so many different rooms, so it is not possible to manufacture such speakers on a commercial basis.
Not far fetched:
If you have problems, or let's say challenges because it can be fixed, with a wonky FR, you fix that with EQ. That in the mentioned bass area but also higher up in frequency if necessary. If the speakers are EQ friendly, that is, and that is something that many people, here at ASR anyway, now check before buying.
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Incidentally, speakers that measure poorly, let's say high distortion, can sound better than low distortion speakers if the latter has a worse FR. So it's a question of how to weigh what is measured against each other by importance.
Speakers with narrow or wide dispersion. There, speakers measure differently. It falls outside the scope because it can be considered both good and/or bad. It depends on taste and preference.