I guess I just fundamentally don't agree with the idea of "fake" meaning "bad" (one of the handful of reasons, I suspect, that I don't experience imposter syndrome).
I think I do in at this current point in time but in order to get there I needed that security blanket that I've mostly let go. And it has proven to be an extremely useful tool to get me out of an extreme situation.
I don't even think you're wrong at all and I think people who go through it will almost always come to the same conclusion of ~the magic was in me all along~ (the magic being self control/courage). But it's hard to quit certain behaviors cold turkey and the concept of "faking it" can be an important tool and coping mechanism in those first steps.
I obviously can't speak for everyone in every situation but I had a therapist I saw remotely who shared a similar sentiment with what you're saying now. What ended up happening was that I would feel in control of myself and felt brave and then when I still failed to do basic things like go to the store it was like diving of the deep end and not knowing how to swim. I'd end up spiraling and not even talking to family for months. I felt that my level of self control and courage was simply not as high as 'normal people' and that was that-- like I just had a hard cap.
A friend from an agoraphobia group describe their coping mechanism and it was much easier to transition back into regular life that way. It was like having a hand to hold onto until I felt comfy on my own (and it's still a work in progress but I get better every year). It helped to not feel like every failure was a failure of my character and more a failure of my inability to replicate a character (even though I eventually came to realize the "character" was just myself, unafraid). Its just a tool! I don't, at this point, genuinely feel like I'm pretending much at all -- unless I try things way outside of my comfort zone, then I'll grab my security blanket until I feel ready to let go and see the light. Fundamentally, I know and understand that my "pretending" is just me practicing self control!
Sorry if this is lengthy and too personal! I just have had nothing but positive experiences with the idea you're butting up against and--again-- I think it can be an incredibly useful tool as a means to get to the next step!
It is nice to see other opinions on this though! I understand its not for everyone! I certainly wouldn't recommend it to everyone!