Who are you referring to? Linux or FreeBsd people? I guess both should look to each others'. But it's common to see this in FLOSS, right? Goes beyond namespaces/ isolation.
I don't mean to sound snide, I'm just saying: if your stack is Linux and the container ecosystem (for instance, if your stack is K8s) what would be in it for you to investigate Jails?
You get that resume-driven development is a real thing, right? It's not irrational. Improving your future prospects is a very legitimate reason to invest in K8s development.
I'm speaking against my own interests here; I don't like K8s.
I think the point was aimed at people that want to debate about jails vs. linux namespaces. Not much of a debate if you don't understand the strengths and weaknesses of both sides.
If they're invested in an existing linux container ecosystem and don't intend to change then yeah probably not much gained.
The biggest advantage is an abstract one; it's usually a good idea to have some idea of different ways to solve a problem even if you're going to be mostly (or even exclusively) focused on one particular way. "Narrowness of experience leads to narrowness of imagination" and that kind of stuff.
For example years ago I started runit in a container to run multiple processes (multiple containers was a bit tricky for operational reasons) and some people were surprised: "oh wait, you can do that?" Who knows if my experience with jails contributed to this "idea" (if you can even call it that), but it probably didn't hurt.
