This is just frequency response, unloaded. No distortion measurements, and who knows what changes (well, mostly distortion) when a nontrivial amount of current is drawn, what the power limits are. No noise measurement, no assessment of channel balance, stability, and many other factors. It's still a big leap to get to "sound the same".
But it's definitely better than nothing, and I'd be interested in results for a lot of tube amps and more exotic designs, see how much some are rolling off treble. Or what some amps' bass boosts or other tone controls do. You'd think that this kind of basic info would be more available.