Bingo! It was a common understanding on this board when I was here 10 years ago that you needed a "time blind" FFT system to eq with if you want to do it "scientifically". Any single point averaging measurement is going to be affected by the room and how the various cancellations and standing waves line up at that point in space.
You can do it really old school and walk the room averaging out the sound in your head and eq'ing to get the best overall balance. But averaging RTAs are only good for studio or home hi-fi with a single fixed listening position.
That is old thinking. Now that the tools are available on the entry level gear to begin to mitigate the destructive interference the whole concept has changed. I don't know anyone who tunes a SoS gig with pink noise or an analyzer.
You put on a well known track and walk the room with your iPad and tweak the EQ on the main output. I get much better results than with an old graphic at FoH.
If you have an iPad or an Android download the Behringer x32 app and try it in demo mode. You will be stunned at the ease of use. You can't compare it to a DRPA. BTW the DRPA have been replaced with a model with a graphical interface on a tablet or a computer. Same with band manager for the Crown DSP amps. You can get this even in the low end Crown amps.