It's not that those who reapplied the old concept in new circumstances are not innovators; they are! Much like the guy who rearranged the well known thread, needle, and needle eye and invented the sewing machine, completely transforming the whole industry.
But seeing the old idea resurfacing again (and again) in a new form gives you that feeling of a wheel being reinvented, in a newer and usually better form, but still very recognizable.
There were plenty of ways to do "containers" (via vservers, jails, zones etc) but the concept of image never caught on before Docker.
You could sling tarballs of chroots around and at times this did happen but it was a sort of sysadmin thing to do, there was no coherent "devex".