In essence, copyleft licenses are exactly that. They oblige the author of a derived work to publish the changes to all users under the same terms. The original authors tend to be users. So, a license which would grant this directly to the original authors would end up providing the same end result since the original authors would be both allowed to and reasonably expected to distribute the derived work to their users as well.
This aligns with the reason why some people publish their work under copyleft licenses: You get my work, for free, and the deal is that if you find and fix bugs then I get to benefit from those fixes by them flowing back to me. Obviously as long as you only use them privately you are not obliged to anything, the copyleft author gives you that option, but once you publish any of this, we all share the results.
That's the spirit here and trying to argue around that with technicalities is disingenuous. That's what Copilot does since it ignores this deal.