These comments are intended for new users, and Windows converts. In general the vast majority of computer users are GUI users, and many are quite adept with getting things to work together. In the case of systemd and XFCE this is not always good praxis. XFCE is a wonderfully powerful but simple Linux desktop. Systemd though it has its detractors, is also a very powerful Debian management tool, aimed at future development. XFCE is good Linux. Systemd is good Linux. Combining two good Linux things does not always make a better Linux. Vinegar is good for making salads. Baking soda is good for making biscuits. Mix vinegar and baking soda together and all you get is a fire extinguisher.
Many things like autostart, and root permissions in XFCE Debian do not always blend well with systemd, not because either Linux is a bad Linux, but because both are good Linux, good Linux for what they are designed for. Often this means some applications configured to run out of the box with systemd need to be changed to work well with XFCE, and vice versa. Some of them such as Thunar with root permissions, drop box, and others, are configured into whatever operating system permissions are involved, for instance Debian running XFCE, or Debian Jessie default. When you change things from the terminal to increase functionality often the changes will succeed at first, but either not persist through reboots, as is the case for remotely using versions of Thunar open as root file manager in Debian where root Thunar is persistent through the session, or not display proper desktop functionality as is the case for drop box, or not persist at all except for the root permissions which will from XFCE in Debian force repeated reboots usually once for every file deleted or moved remotely with Thunar root, because root login is not possible from Debian (systemd), and the saved actions have to be reconciled one at a time before XFCE in Debian will allow normal login again. There are many reasons why Debian does not ship with XFCE as the default desktop, and nearly all of them are because some applications designed to be compatible with XFCE in Debian cause problems with systemd configurations for Debian. Neither Linux is bad Linux.
Finally, as Debian continues along its path of hardening its systemd, conflicts are going to be discovered by users concerning applications hardened to XFCE Ubuntu based distros. By sheer numbers of users, Ubuntu, and Ubuntu based distro users are probably the greater number, and probably at least half of that number use XFCE. This does not mean XFCE is the better more secure system, or the better Linux. It just means, it takes all kinds to make a world, even in the Linux world. The systemd ball is in Ubuntu's court concerning XFCE, and rightfully so. Debian is committed to systemd and gnome at least partially for Ubuntu development's sake, but it is also in the XFCE developers' court as far as continuing with a desktop version for Ubuntu. If you don't understand the differences in the system topology between Debian systemd and Ubuntu based distros running XFCE, it's best not to tinker too much with systemd on your Linux Lite system. It is here to stay, but XFCE and Ubuntu may or may not always play well together in the future, and I don't know if that situation is going to change or not. Ubuntu certainly has growing pains in some areas, and XFCE has resource shortage pangs. Who knows.
TC
