Some room issues can't be changed (for any of a number of reasons). At that point, I'm just saying modern EQ functions in HT are behind the times, but catching up
That fits with the current model.
As an example, I have a huge peak in my room at 52 Hz. Since it is so low, I cannot effectively treat the room. It also happens that the peak shows up through most of the listening area. The peak is caused by room modes and is addative (a summing of waves). Those three things together make it an ideal candidate for equalization.
I also have a null at 71Hz. It also shows up in most of the listening area. However, since it is caused by cancellation reflections, EQing is not going to do a thing for it as any changes in the signal will equally affect the direct sound and the cancelling reflextion(s).
A third example: Suppose you have a peak at one of your seating positions only. You can EQ it, but it is going to affect all your other seating positions as well, so you may actually do more harm than good.
This is probably where EQ algorithms are just recently catching up. Whith more measureing positions and better algorithms, your system can probably make better decisions on what to EQ and what to leave alone.
I think the main reason that EQ is frowned on higher in the frequency band is that the peaks and nulls become more complicated by reflections. It becomes much easier and more effective to treat via absorbtion and diffusion. Unfortunately its not so inconspicuous.
In the 70s EQ I think was considered a one size fits all solution because we did not have a solid understanding of the causes of frequency changes in room. Now that the causes are better understood, EQ becomes but one tool in the chest.
