It's true that some kids are naturally better than others at doing tasks that school and future employers have deemed important. There's no reason to call it "gifted." The word "gifted" carries a moral valence that is completely unnecessary.
Though I completely agree that not providing a track for these kids to go as fast as they can is wrong.
I know "gifted" is not a monolith and I suppose finding other terms using a thesaurus might be in order. Children can be gifted across many different kinds of intelligence or ability. I know it's more than just being good at math.
When kids get put in a "gifted" program at school, what exactly is being selected for? It's not general intelligence, as plenty of smart kids do poorly in school. It's not, say, athletic ability. There are sports teams, but not programs for "gifted" athletes in public schools as far as I know. It's not emotional intelligence, or empathy, or any of a number of axes that a child could be "gifted" on. It's their ability to follow instructions, and sit quietly, and pass quizzes faster and more accurately than everyone else. It's a very specific set of skills that is necessary to succeed in school.
My entrance to the gifted program was not based on my ability to follow instructions, sit quietly or pass quizzes fast. I failed at all 3 of those. I excelled at a series of tests on solving puzzles and pattern matching.
Having been through an 80's gifted program, selection was based on standardized test results (98th percentile scores) followed by in-person, interview-style IQ test administered by a psychologist.
From what I remember, the interview focused on pattern recognition. "Here's a picture: tell me what's wrong with it?" "Here's three shapes, which one of the others comes next?" Pattern recognition is considered a proxy for general intelligence, right or wrong.
Though I completely agree that not providing a track for these kids to go as fast as they can is wrong.