Of course they cannot reasonably comment about the sound of the particular component, just as someone auditioning components via Youtube cannot reasonably comment about how the gear sounds. But, they can otherwise reasonably comment on the gear-- the design philosophy, the price charged, the lack of credibility of claims made by manufacturer or those reviewing the gear, etc. (everything but the sound). It is reasonable for the OP to state his opinion that only the sound matters, but, others might reasonably disagree and think that minor details, such as the price, matter and that certain price levels cannot be justified no matter the sonic result.
