[Griefbringer]

Perhaps what the person meant is the lack of ability to have "no unit (at all) selected" at a given time?

The current set-up where you always have a unit selected can sometimes lead to unfortunate moving incidents if accidentally clicking the mouse at an unintended moment (e.g. when just browsing the map and making plans), or accidentally clicking at a wrong hex when trying to access a certain unit (granted, this can be avoided through keyboard or HQ commands, though they may feel less convenient). These have happened to me a few times, sometimes leading to unwelcome results with a unit moving when I did not want it to, or in a direction that I did not want.

Not a major issue overall, though I guess it could be at times be convenient especially for beginning players to be able to view things without needing to worry about accidentally moving things. Granted, there are some workarounds such as viewing the map through the bombardment menu.