I open and use Host1, Host2, Host 3. Over time each gets closed. When the last is closed, no screen is displayed, just the app Title Bar. I can to cmd+N to get the "Hosts" screen again, but why? When the last host screen is closed, simply redisplay the "Hosts" screen.
This is the behavior most users predict, multiple-tabs apps (Finder, Safari, etc.)shipped by macOS are all close window instead of open a default screen.