I'm in agreement with that; in a way, it's a superset of the point I was making. What is or isn't "you" feels variable, fluid. An experienced driver might find that, when driving, their sense of self extends to encompass the car. I definitely felt this when getting into "state of flow" while playing some first-person videogames. The ideas of "state of flow", "immersion", "becoming one with something", all seem to point to, or in some cases be a case of, the fluidity of the sense of self.
> Going deeper still points to the feeling of “I” being nothing but a useful illusion, and most importantly, just another feeling that you experience alongside other feelings like happiness or anger.
Useful illusions is all we have. As for "just another feeling", I can entertain that thought, and I find it curious, but I haven't really experienced this frame of mind/perception yet. Or maybe I did, but I didn't realize it, so I don't have the memory associated with the phrases you used?
> This is not a metaphysical claim, but a more broad statement about the systemic factors that influence what it’s like to be you.
I appreciate you going for the more "materialistic"/non-spiritual take. I'm not denying the variety and richness of experiencing the world and one's self in it. I was just taken aback at both broad dismissal of "brain / body separation" and it being justified entirely by spiritual and experiential reasons. My point about driving meshes with my other comments (including this one) like this: we know the "sense of you" can be extended to and beyond the body. But if, instead of extending it, you try to contract it, then without crossing into metaphysics, you'll stop at the brain. This is what I believe makes the brain/body distinction meaningful: not what you can make part of yourself, but that which you can't take away.