I also mentioned that UNIX could in principle do this, though marketing considerations often limited the theoretical capabilities of a UNIX system. Linux is free of annoying licensing games, and it's possible in principle to set up a large site with shared Linux systems. It has most of the advantages of a commercial UNIX, without the licensing complications that inhibit making good use of the client-server philosophy. For example, it's possible to have a university computer lab, or office machines, with no disks, which boot off a server.
Users can choose whether to run applications on the local machine or off the server.
If you want to run locally, you launch from a local login session. If you want to run remotely, you launch off a remote login. The choice here is very much up to the user. The standard way of running programs does rely on the user to know where to launch a program to force it to run on a specific machine. All of this is very nice and convenient, and Linux is growing rapidly in popularity.