IOW, the social risks of whole grade acceleration are also related to a self-fulfilling prophecy/feedback loop. If more children were allowed developmentally-appropriate whole grade accelerations, there would be less social stigma and fewer negative social impacts, but institutions tend to be opposed to grade skipping because of the fear of negative social impacts...which leads to fewer children being grade skipped...and thus greater negative social impacts of grade skips...
But again, at the individual level, it is always a complex risk calculus, even taking only social development into account, balancing social mismatches due to disparities with chronological age-peers resulting from intellectual development, with mismatches due to disparities with developmental academic peers resulting from biological development. And, of course, the range of actual social-emotional development in both GT and NT students is extremely wide, as anyone who has worked in a middle school can tell you.
And FWIW, I was three years young for grade during the years I spent in high school, and found that my slight personal distance from relationship drama made me a go-to sounding board and voice of reason among my classmates. Of course, I've gone on to a career in mental health, so this might not be representative...
