That is the thing, there is no standard, and if there was a standard, who as the right an authority to make that standard? Who will enforce that standard?
What happens when all Audio equipment sounds the same? What now, do we now base our purchases on audio gear according to "color" or "size?"
It benefits a company's image to state intended design goals and what steps were taken and what compromises remain in achieving those goals. In this way a company creates it own standard by being specific as to what is trying be accomplished. This matters especially for products that claim to be reference or accurate because otherwise the claim as it stands doesn't mean anything at all. Reference to what?
Most products don't aim towards flat so a scenario where all products sound the same is unlikely. Products that aim for flat should address the above.