"Application containers were born out of a variety of reasons, but primarily seem to be oriented around partitioning a host OS into individual resource namespaces each with its own library context. Thus, an attempt to address the fact that the host OS is deficient in providing a multi-tenant experience out of the box."

Given that multi-user and multi-tasking is pretty much a massive hack on what is at the core a single task, single user design, no surprises there.

I say a massive hack, as a CPU is in essence an assembly line. It takes data and processing directives in one end and spit processed data out the other. What multitasking does is basically to halt the assembly line mid job, documents its state, clear it out, and then load onto it the state of a different job. And so it goes, cycling through all the tasks.

Then again, the apparent reason for the discontinuation of Consolekit in favor of Logind was that the latter, via its ties to systemd-as-init-and-cgroup-manager-in-chief, was multi-seat.

A concept where one pretty much recreates the mainframe on the desktop by logically assigning disparate IO devices to a "seat", and so in essence creates terminals. Apparently this is supposed to work while still maintaining the ability to plug and unplug IO devices at will. Quite the rabbit hole.