Though not quite the same, IIS application pool isolation (separate app pool and worker process for each website - which is the default from IIS7+) gets you a bit of the way there. This has improved security, performance and reliability massively for us.
But yes, speaking as a shared webhoster devops kinda guy, I agree, it would be nice to have containers on Windows too.
Seriously, if MS can be persuaded that this appraoch is beneficial for their ecosystem too, then everyone is a winner!