That's a praiseworthy intention, but I don't believe it works in practice, and I really don't believe that any current process for selecting 'gifted' children is effective. I'd also draw a stark line between 'gifted' programs and what you describe
> but an intelligence test coupled with subjective teacher evaluations is the best way we do have to identify which tracks are appropriate for which children.
I'd call the above streaming or setting, and it's definitely valuable/effective. However, it doesn't need to be tethered to any system that focuses on labelling students. 'This is the stream you are currently in' is a very, very different idea to 'this is who you are', particularly for a child.
> being in an 8th grade classroom where teaching algebra has been banned because it's too advanced
This is definitely a problem, but I think it's best solved in other ways, rather than a poorly-supported regressive policy.
Gifted & talented programs often have positive intentions, but every implementation I've ever seen or heard of just reinforces existing systems without actually having a positive impact.