In short: No.

In X11 "screen" has a particular meaning, and only supporting a single screen doesn't preclude multi-monitor support or virtual desktops.

Is this why back in the day sometimes a Linux distro would have a multi-monitor setup where each monitor was an actual different desktop cube for example. There was a time when each window for an Nvidia graphics card in that type of configuration could not be moved from one screen to another, etc.