Some people don't work with containers in their job nor as a matter of course. I always liked vagrant because it orchestrated the estate you're often handed in many environments. I think sometimes we lose perspective because we’re often early adopters (and technology experts on top of that) when a good majority of the environments you may walk into (am I the last of the consultants out here??) have no container estate at all. Then there's dinosaurs like myself who prefer to work in hardware and VMs. When a lot of folk were jumping on the immutable infrastructure train, many others were deepening VM knowledge and experience due to large outlay by their companies (or clients) on VMs. If you're good at it, you can be so busy with the one that to stay up with your money-maker that you don't have the time to dig into the new hotness (especially if you have a family).