When I used to sell gear years ago, blind listening tests for customers, though flawed for reasons the OP described, were the best tool available to help a customer decide what they liked best, AT THE TIME.
But Time Always tells.
From a buyers perspective, the best approach is to train your ears by listening to a lot of music as much as possible, as many ways as possible, then use that as the reference for determining where things stand with your setup. Then tweak and tune as needed to hit your target. Meanwhile, keep on listening along the way to as much as possible as many different ways as possible to know how things can and do really sound. At some point you will know the target when you hear it, and it probably will not even change very much, and only then will you be in a position to bring the hunt to an end.
SO the key is to know how your gear sounds and compares to everything else. BLind a/b listening tests are not needed.
But Time Always tells.
From a buyers perspective, the best approach is to train your ears by listening to a lot of music as much as possible, as many ways as possible, then use that as the reference for determining where things stand with your setup. Then tweak and tune as needed to hit your target. Meanwhile, keep on listening along the way to as much as possible as many different ways as possible to know how things can and do really sound. At some point you will know the target when you hear it, and it probably will not even change very much, and only then will you be in a position to bring the hunt to an end.
SO the key is to know how your gear sounds and compares to everything else. BLind a/b listening tests are not needed.

