A TLDR on iptables/netfilter would be pretty awesome.
switching around Desktop environments
The simple answer is that systemd is not the Unix way.
Linux is Unix-like but not Unix. There are some that would only describe Linux as being Unix if to stood a long way back and squinted. Whatever your standpoint on the Linux kernel it was inspired by Unix and the Unix-way.
For some of the greybeards, systemd is blasphemous.
This argument became heated within Debian when they discussed if they should move to systemd. As Debian is Open-Source that argument was held in public for the world to see. Some people were so upset with the decision to go with systemd they forked Debian into a new distro. Arch is in love with all that is new and shiny, as such it embraced systemd early on. Many others have followed over time. There are however some that never will, there are some people that never will systemd. To the point that if there is no Linux distro left that is systemd-free they will probably make the move away from Linux to BSD. For some of the greybeards, BSD is looking more and more like home as Linux changes over time.
Whatever your standpoint it is an interesting subject to study. From the nuts and bolts of how things work. The Unix-way and why systemd is so egregious. To the way, an open-source project the size of Debian goes about discussing contentious changes. It's interesting on many levels.
