With medicine it boils down to a dismissal of folk remedies as placebo.
But with computing its because the old ways were developed on mainframes and minicomputers in an environment that current generation may only have heard stories about.
This because the micro-computer era was pretty much a mental reboot for computing, as little if any software crossed over (until fairly recently).
But this happens in other areas outside computer science. For example, modern medicine rediscovering old medicine "recipes".
The problem in our field is when people talk all day about Docker while surpressing LXC from the discussion.