Yeah I don't know that much about dac but say headphone for example. People look at response graphs which shows how much amplitude at this frequency.

So it's like saying Honda driving at 40 miles/hour measures the same as Porsche driving at 40 miles/hour, and the same when both car are driving at 60 miles/hour. Therefore Honda and Porsche performs the same lol.

And as you said the response graph people read are the oversimplified version of a very complex matter that needs much more other measurements to compare. Like how fast does it react to change in load, how well does it handle complex signals.... Etc.

But yeah I'd imagine dac is probably similar in that regard.