Suddenly plasma-desktop was missing?

This isn’t an actual request for support but out of curiosity about what has happened to my system.
I updated my system and removed orphaned using “pacman -Qtdq | sudo pacman -Rns -”. After a reboot the plasma desktop environment wasn’t starting an xinit/startx gave an error. I tried editing the ~/.xinitrc and eventually noticed that plasma-desktop wasn’t installed at all. After installing it everything went back to normal except that I had to customize my taskbar. So I was wondering, did I accidentally uninstalled plasma-desktop when removing orphaned packages? What has happend?