We are not talking about adjusting the speaker channel levels or distance or crossover or speakers and subs configuration. We are talking about equalizing the subwoofers and speakers, and manually doing that is almost impossible unless you have the right measurement tools and knowledge.
I used to think the same with regards to Audyssey for the last 15 years or so. But after I used Audyssey Dynamic EQ, swallowed the red pill, and woke up from the Matrix
, my eyes are now wide open. That is why some of us are making a big deal of it. The difference is unequivocal for some of us, not subtle.