Why this worry is reasonable
Concern
The assignment stopped measuring what it used to
For as long as most of us have been alive, a written assignment did two jobs at once. It produced a piece of work, and it produced evidence that a particular child had sat down and thought. The second job was the point. The essay was never really about the essay.
A tool that returns a finished, fluent, correctly structured piece of writing in about twenty seconds pulls those two jobs apart. The work can now arrive without the thinking behind it, and it arrives looking exactly like the version that took four evenings. If that feels like the ground moving under something you understood, it is because the ground moved.
Noticing this before schools have finished responding to it is not alarmism. Most of us learned to read a child's progress partly from what came home in the bag, and that signal is weaker than it was. Nobody has handed out a replacement.