Educators that have low expectations for certain students will not challenge them and hold them accountable for their work and studies.
I found this true even as a student in the 'gifted and talented' program through high school and most of middle school. It wasn't until college (and even then only math/science/cs classes) where I was really challenged.
I suspect quite strongly that what we today call "gifted" is really about what the average child should reach, and I don't care to even guess at what the true upper end of truly gifted individuals could attain in a teaching environment that is actually properly designed, rather than being handed down from on high by our 19th century betters.
I found this true even as a student in the 'gifted and talented' program through high school and most of middle school. It wasn't until college (and even then only math/science/cs classes) where I was really challenged.