I've been using FreeBSD since around 2002 (including Jails), and the mentioned problem is still why majority of readers or Docker users have never ever heard of FreeBSD Jails, though it was released about 14 years before Docker. It just never took off for casual users and it was far from 'fully packaged product' back in a day. It got better, but it still suffer from the same problems as as it was 19 years ago. And partly because FreeBSD core team have a specific view on it.