When I was younger and read Stereophile and Absolute Sound every month, I often felt that when reviewers either listed their equipment as reference or the device they were reviewing was called reference, it meant several things to me; it was out of my price range, it must have some unobtanium sound qualities that only few people get to experience, and the company received some publicity based on the magazine review.
As I got older, I learned, and as others have stated, it can be either objective or subjective. Who makes the determination if a product is to be called reference? Lately, some audio companies are pushing out their so called reference products at ultra exotic prices. So, perhaps, the audio industry is in some ways pushing reference products from their perspective and people who are interested in absolute state of the art by said company, are buying these products. The reviewers have a new reference product to review. But, when did reviewers start arbitrarily start calling products they reviewed reference? Or, why do reviewers call their system reference when reviewing components? I can easily say I have a reference system too. In fact, I reviewed xyz, and used my reference system consisting of McIntosh MC2301, octave Jubilee reference preamp, Transrotor Apollon TMD turntable, Clearaudio MontBlanc stand, and Shunyata power cables. In my humble opinion reference as used by reviewers indicates a level of experience where differentiations in equipment can easily be identified and extrapolated whereby a review uses the superlatives we often hear describing high end or reference products.
I give up...too much to ponder. Reference is what anyone wants to call it, therefore, my system is a reference, yours is a reference because after all, you are comparing it to everything else. One last thing, what is the baseline to match the reference statement? Is it technical specifications, sound, build quality, etc.? That seems to me, at least from my foxhole of experiences, the confluence of definitions.