Generally I agree with you.

The part where I disagree is the 'why' and the 'who'. There are a number of very strong forces (aka lobbying groups, aka decisions like 'no child left behind') doing their best to destroy the public school system. By making this conversation about gifted vs not gifted, we are again distracted and pitted against ourselves.

Public schools should be well funded and funded in an egalitarian manner that doesn't replicate residential aggregation of race or money. It should be funded for kids who need remedial help, help appropriate for their age, and help because they're advanced. It should be funded so that people who move from one group to the next, and you can and do move from one group to another, are supported

IMO the goal of the lobbying and shit policy is to make private school the default option for those who can afford it and those who can barely afford it. Public school will be left to the masses, and will be defunded leaving a populous more easily controlled, with less social mobility.