Most of high end preamps don't even have tone controls and all amps sold in Best Buy do. This alone should suggest something.
That audio purists are masochists and would rather buy several amps until they get what works in their room rather than tweak a few db with a tone control? Just kidding LOL ;-)
Tone control destroys imaging, clarity, and even tone. It changes harmonic structure by improper summing of harmonics (high quality constant group delay Bessel like adjustable filters ain't cheap).
In EXCESS absolutely - but most tone controls are used very lightly - or at least they should be.
Purists would also say that capacitors shouldn't even be in the signal path.
They should use active speakers in this case (and actively powered by amps that do not use coupling capacitors in the signal path)
In addition - system should restore original concert performance. So here is the question: How do you adjust treble when you are at the concert?
Yes but...the mix engineer and mastering engineer has already monkeyed around so much with what you hear that this "purity" goal becomes a "mute" point. (And these guys start by selecting mikes and placements that help create the sound they desire from the get go - so there is never "purity" to begin with)
Another way to apply this "purity" logic would be to say that "I want to hear as close as possible to what the recording engineer hears". In this case buy the same equipment (speakers are the most distorting) as are used to mix/master your favorite music - or get what your favorite artists likes to use. At least, then you can conclude that you are perhaps hearing things a little closer to how they were intended to be heard. Although, I'll admit even this is a weak argument and not as strong as the logic that says "I'll use _______ because if it is good enough for "- insert your favorite classical audio label -" then it will be good enough for me." Kind of a Stereophile A list approach, however, without the nagging concern that stereophile makes money from advertisements and therefore has a vested interest to have an all inclusive extensive A list.
Good discussion....tone controls have caused serious angst with audiophiles for many years and no doubt will continue to do so.