I'm not GP, but if I were to hazard a guess, they want something more than just mount space isolation. Something akin to BSD jails, without the bells and whistles of OCI containers like overlay filesystem, network virtualization, resource management, etc.
That requirement is pretty legitimate, since its easier and suitable enough for many applications for which we currently use OCI containers. For example, isolated builds, development environments, sandboxes etc. (I have an isolated build tool for Gentoo).
But Linux already has multiple solutions that fit the bill, like systemd-nspawn, LXC, bubblewrap, etc. Too bad, they aren't as widely known as chroot.
None of those things do what chroot does but many of them involve chroot - so I'm still not grasping what "better chroot" is, other than "not chroot, but something completely different."
One annoying part of using chroot if you're creating them on the fly is teardown - you have to manually invoke umount, and also take care to get this right for partially created chroots (maybe you detected an error after mounting proc, in the process of getting other files in place).
This was my original motivation in creating machroot (mentioned elsewhere in this thread) and having it use namespaces.
That requirement is pretty legitimate, since its easier and suitable enough for many applications for which we currently use OCI containers. For example, isolated builds, development environments, sandboxes etc. (I have an isolated build tool for Gentoo).
But Linux already has multiple solutions that fit the bill, like systemd-nspawn, LXC, bubblewrap, etc. Too bad, they aren't as widely known as chroot.