"it is kind of waste to have 'n' copies of the OS loaded, so containers are a 'semantic' fractioning of the resources where the OS is common but the set of processes are unique to a client. You still need a way to allocate from the single set of resources so containers provide that abstraction."

Agreed. What I find so odd is that this problem was simply and elegantly solved in BSD with 'jail' and everyone went about their business.

I do not understand why (what appears to be) the linux answer to 'jail' is so complicated and fraught and the subject of so much discussion.

I am not sure that containers and their build scripts represent the $huge_profit_potential that people think they do ...