I use eq to voice the room. Some spaces I have measured have standing waves boosting certain low frequencies up to 20 db or more, muddying and even masking some the bass frequencies and with harmonics, also affecting the mid range. Using the eq to fix the room gets its affect out of the listening experience. Some will argue an equalizer will introduce phase distortion. Everything is a trade off, but I'll suggest getting a 20 db hump out of a room has a bigger impact on sound than the potential introduction of some distortion.
Once the room nodes (humps and dips) are smoothed, I leave things alone and use the tone controls on the pre to adjust specific recordings to taste. I have found with properly set up speakers, use of the tone controls is necessary less often and/or to a lesser degree.
Using eq to adjust every song is like using the eq as a tone control, which is OK, but not necessarily equalizing the room. I agree using eq to cut humps is preferred to boosting dips.
All that being said, some hobbyists prefer to tame room problems with various treatments, a different way to solve the same problem. Whatever works is all that matters.
I have eq'd every channel in my stereo and home theater. If anyone wants to listen, let me know (there is always cold beer in the fridge)