There isn't anything new, but it's also worth remembering Mark Twain's quip: history doesn't repeat itself, but sometimes, it rhymes.

FaaSes do add some twists on CGI. In CGI the short-livedness is the process, in a FaaS it's the container. A CGI program can get away with relying on local modifications to a file system in a shared environment. FaaSes somewhat point away from that.

There's also the speed of scaling. Insofar as FaaSes rely on lower layers to insulate the layer between process and machine, it becomes plausible to grab a number of machines relatively quickly. There's a cold start cost, to be sure, but the cold start on "launch this container" is probably better than "install this software and then launch it".

I don’t disagree that FaaS and CGI are wildly different but I’m not sure I understand your distinction between containers and processes. Containers are processes decorated with networking namespaces, control groups, and chroot.

The thing I'm driving at is that containers create much stronger isolation than shared hosting does.

Both are processes, but the administrative overhead is lower when you can contain the blast radius with namespaces and cgroups. The illusion of isolation is much more complete to the containerised process than for an uncontainerised one.

That's a good way of looking at it, thank you.