[ww520]

What I was talking about is the multi-user as a capability to run untrusted code. You were talking about it as a policy and procedure. The multi-user capability allows one to use permission to create a lock down, low privilege area to let anyone to run in it. There are open Unix accounts out there that allow anyone to log in to play around with it for a long time. The multi-tenant problem claim is just not a valid one.

[camuel]

If all is that simple & rosy why no hosting/cloud service uses it?

Why entire shared hosting industry custom-patches their kernel constantly with OpenVZ and stuff?

Why shared hosting has such a bad reputation for being insecure (despite all efforts).