I use PCLinuxOS as my primary Linux OS. They are a bit conservative to adapt new updates until they are sure of stability because of rolling nature. KDE is still at 5 there. Heard about Neon and wanted to try KDE 6. I find that they have adopted Windows style approach to updates where we need to reboot to apply the updates and we cannot do anything on the system while the updates are processing. Recently managed to install Fedora because I heard that their EFI is secured or something and can survive clobbering by Windows updates in a dual boot setup. But they also seem to have gone with offline updates.
Are offline updates necessary due to them using SystemD or is the Linux world in general moving in this direction?
It does sound like a good idea.
Mid-update you can end up with broken dependencies and thus not fully working system. There may also be a problem with how programs update their config files.
This is especially true with big updates which is why Arch and Manjaro recommended to update from plain TTY during the Plasma 6 upgrade. Reboot, do not login, switch to TTY, stop the graphical login manager, just then proceed with upgrade.
A bit too much to ask for from regular users. Especially since it relies on them reading update announcements before each update.
Personally, I always close most stuff during updates. I even had terminal emulator itself die during update on Linux Mint.