I found out in 1978 with the purchase of my first RTA, after discovering about the benefits of voicing ( equalization) of a sound system via a book called Sound System Engineering.
To address the room`s nodes and to smooth out their frequency unnatural peaks via "attenuation" at their and adjacent frequencies via equalizers 1/3rd octave type preferred, and not try to tune the systems bandwidth flat by boosting the speaker`s natural frequency roll off at the bottom and top octaves.
Once I started voicing my home separate component based system I became more aware of the inherent unnatural sounding coloration of those room`s nodes after removal, or at least decently tamed, the reproduced sound of the stereo became more natural, smooth and balanced sounding with those frequency peak`s colorations tamed down.
And then I moved on to using the RTA & equalizers with live PA systems with the same positive tonal results, plus the ability to raise the SPL of the mains, and especially the problematic on stage monitors to higher SPLs before feed back.
Since 1978 I`ve voiced countless folks stereos, including every one of my own and other folks and my own PAs manually until 2010 when I purchased my Integra A/V/P which has Audyssey for my living room`s system.
Prior to that Integra purchase and use, I very carefully manually tuned (voiced) my living rooms reference via quality 1/3rd octave and using a Class 1 quality 1/3rd octave RTA/SPL analyzer to +/- 2 db following the natural systems mild frequency roll off at the top and bottom octaves by taming the room`s peaky nodes back in 2003 when I purchased the living room`s Mc. XRT-30 line array tri-amp capable speaker system, so I had 7 yrs. of listening to that system manually voiced (equalized) before I had ever used or experienced a automated voicing equipment such as Integra`s integral provided Audyssey.
After I disabled all my HT system`s 7 channels equalizers and ran the Audyssey EQ voicing & speaker distance timing program, in my situation, the overall SQ was perceived by my visiting audiophile friends and myself to sound even better than my well experienced manually doing so, and with the use of HQ Pure Audio BR discs the system`s speaker system`s presence totally disappears and the performers appear to be located in the middle of the living room`s floor in front of the listening couch, whether the system was in the 2 channel pure direct mode, or surround mode, as selectable via the BRs menu.
I have not felt the desire to return the system back to 1/3rd manually voiced equalization.
I learned over the yrs. there are some folks that desire the room nodes, and feel somethings missing when the unnatural colorations are removed via equalizers, and most of them generally prefer the smilely EQ type tonally, and that`s ok with me, their system their choice.
In closing, I learned over the decades, it is mandatory, or at least the best practice, to initially set up the sound system to get the best possible sound as possible before any EQ voicing is attempted, whether manually adjusted, or using any automatic type program, as the voicing is the icing of a properly baked cake for best results, and avoid boosting any EQ frequencies while manually voicing.
Properly tuned when level matched between EQ in and out, only the un-equalized peak colorations (room nodes) removal should be apparent thus maintaining/preserving the system`s electronics signal to noise ratio.
Enjoy your music as you see fit, folks.