A fact is a fact because it has been demonstrated.
If a friend comes telling you that his neighbor is a space lizard, I expect you to ask for evidence before you start making plans to hunt it down.
But come to an audiophile forum, and feelings under sighted conditions become the gold standard of truth? No.
Ideas, feelings, facts, they deserve to be different words. Under sighted conditions, I may get the feeling that my latest DAC rolls off the treble. I may get some idea about why that design could cause treble roll off. But do I have facts about treble roll off or its cause? I do not, and if I act like I do on a forum, I’m kind of a fraud.
If I don't care, fine. But if I do care, and wish for the truth about treble or my actual ability to hear it, then I will need some controlled experiment to gather actual facts.