We don't have the technology to collect the necessary data to be able to test hypotheses for psychiatric and psychological phenomenoms, and even many other non brain related medical claims about the human body.
https://en.wikipedia.org/wiki/Replication_crisis
Seems pretty reasonable to take claims about unverifiable subjects with a grain of salt.
However, if you were unlucky enough to suffer with a completely debilitating mental illness, and all you have to treat it are a series of therapies that appear to work for some people, would you not try them?
Trauma therapies like EMDR and CBT can save or transform your life. Maybe they work no better than crystal healing or prayers for some people, but if your life was derailed I bet you would try anything...
Would I have to give up on my scepticism to do so? Why?
If I was in distress, and if there was no well-proven treatment available, I'd probably have a go provided the therapy wasn't actually a scam or actively harmful. I'd probably even attempt to engage with it honestly and openly.
But I'd temper my expectations based on the lack of reproducable evidence.
I mean people would even try those with enough distress. And to be fair a lot of surprising innovation comes from people trying those! But of course mostly they're a scam or actively harmful.
It's the equivalent of basing nutrition science on a Pew poll where people self-report their favorite food.
Sure, it's useful to know people's general preferences sometimes, but for science that data is junk.
Also, falsifiability is broadly rejected as solution to the demarcation problem.
I honestly think a lack of grounding in philosophy of science leads people to draw the line between science and pseudo-science based on nothing but vibes. For example, I've seen people reject mainstream psychiatry as totally pseudoscience and then endorse evolutionary psychology, a field with a huge bullshit issue.
Both of those have huge bullshit issues, that is the problem with such sciences you have to pick your poison and that guy just picked another than you prefer. Big things like stereotype threat turned out to just be bullshit, but you still see people believing in it since they want to believe in the idea rather than whats actually real.
Edit: Also almost everyone resorts to evolutionary psychology arguments when it suits them, such as why so many eats themselves fat etc.