are far older than 2005. It has been reworked several times, and the last iteration wast released 2005. It stems back from 1999.
Anyway, this Linux tech seems it is heavily inspired by Solaris containers. The cool thing about Solaris containers back then, was it remapped all kernel calls to the Solaris kernel - this was new. So when you installed Linux Red Hat, it would remap all Linux kernel calls to the Solaris kernel, so only one Solaris kernel was active no matter how many Containers you booted. Each container only cloned a few kernel data structures in RAM (40MB RAM), and also cloned the filesystem (100MB) via ZFS. So Containers are really resource saving, that is the point of Solaris containers. One guy booted 1,000 containers on a 1GB PC back then, it worked but it was really slow. Now, this Linux tech seems awfully similar, just like systemd is a clone of Solaris SMF, Linux btrfs is a clone of Solaris ZFS, Linux systemtap is a clone of Solaris Dtrace, Linux open vSwitch is a clone of Solaris Crossbow, etc etc etc.
It would be really cool if Linux developers did something new themselves, instead of cloning what others have done. For instance, the Linux "RCU" which is presumably cool according to Linux developers, turns out to be patented tech from IBM. So, RCU is not an invention by Linux devs either. BTW, did you know that the "Linux" kernel itself, is a clone of Unix? Everything in Linux is a clone, nothing is new?