My dad once told me that being smart was a curse in some ways, but he framed it as having a World view that few others had.
I think however your take on it is closer: when you're smart, you're told you're smart (both as a positive and as a negative - I was bullied for it), it just becomes part of your self dialogue and identity and it gets in the way.
It's taken years of therapy for me to get to the point where I realised none of that really mattered as much as having great relationships with people I liked, and going for long walks in green spaces and not thinking about anything.
RE self dialogue: I think it is also self-reinforcing in a positive way. "I am competent and capable of this" is certainly less distracting internal dialogue than "maybe I'm not smart enough" to children. I believe most adults eventually get better at ignoring this type of thing altogether, since it isn't really useful or productive.
Parenting philosophy rooted in growth mindset advocates less for "I am smart and therefore I can do this" but rather "the hard work that it will take to do this is worth investing, and failures along the way are opportunities to learn rather than judgments of whether I'm good enough or should continue."
Having great conversations with Uber drivers, coworkers, and online folks (nothing can compare with real life interactions due to a few concussions), and walking a nature trail every so often has done many wonders for my mental health where I thought I was unrecoverable.
I think however your take on it is closer: when you're smart, you're told you're smart (both as a positive and as a negative - I was bullied for it), it just becomes part of your self dialogue and identity and it gets in the way.
It's taken years of therapy for me to get to the point where I realised none of that really mattered as much as having great relationships with people I liked, and going for long walks in green spaces and not thinking about anything.