It's all about the difference between treating the symptoms or the cause. And 99% of the time the cause is the room. If you have money to spend solving the problem, you will ALWAYS get better value from spending it on treating the cause (the room) than the symptoms. And even if you happen to have a top quality, stereo, 1/3rd band per octave EQ unit free doing nothing, you would be better off selling it and spending the earnings on acoustic treatment than trying to use it to EQ the problems out of your room.
Or, to paraphrase Scottie on Star Trek, you cannie change the laws of physics.
With live sound it's a different matter entirely. It may not be perfect, but you can get away with EQing 'the room' out of the equation.
When the going gets weird, the Weird turn Pro.