If you're using App Engine, the number of frontend servers ("instances") is a config parameter. The fact that your app runs on multiple servers is implicit in API's and runtime environment because they don't allow you to do some things. But you don't know the names of the machines running your app, you don't get any server-side shell, and don't have any unix commands to run (except on your workstation if you use unix). Instead you upload your app and set the version that's live.

I completely agree that "serverless" is an annoying buzzword and I hope it doesn't catch on, but there's a difference between this sort of environment and managing a collection of virtual machines yourself (I've done both).