I think the null hypothesis and the burden of proof applies to a specific claim that "this is how it works". There are plenty of phenomena "officially" unexplained by science yet, and that's ok. But claiming that some cards have some magical meaning doesn't make sense.
True. Calling BS on magic is fine. But it could also be wrong to claim tarot is complete BS. It's possible the effects of a tarot reading are explainable by things like observation bias, the subject changing their behaviors due to the reading, or the reader using some sort of body language reading to influence their "interpretation" of the cards.
Let's be clear in our definitions here: when people say "Tarot is BS", they don't mean "it can never get the right result"; they mean "it doesn't get the right result through some mystical, spiritual, or divine knowledge as the practitioners of Tarot often claim it does". Additionally, if a Tarot practitioner does not make such claims, and instead points to any of the psychological explanations you mentioned, then the cards are no longer relevant to the practice anyway since they are not involved in the true mechanisms.
