By your standard, almost anything would be subjective. Let's go through your line of thinking:
The tester chose an enclosure you probably don't have at home. As such, the card will not demonstrate the same values in your enclosure at home. As a result the tests are "subjective".
Power consumption? Well, you've probably got a different PSU. Subjective.
FPS? You've probably got a different CPU, different OS configuration, motherboard, harddisc... Subjective!
In summary: If the tester uses the same enclosure for every card they test, I don't see how it's subjective. Sone or dB as a unit of loudness are measurable, as is temperature. Or do you want to tell us that, say, the distance to Betelgeuze is subjective just because you don't happen to have the proper equipment to measure it?