disclaimer: IIUC, never experienced first hand. /var was originally for network booting machines. / is read-only fileshare and /var is for user storage. /home

disclaimer: IIUC, never experienced first hand. /var was originally for network booting machines. / is read-only fileshare and /var is for user storage. /home -> /var/home too. It's campus wide workstations installation type of thing. So, /var/tmp is kind of wrong, and so is /var/log/messages on a laptop, and besides the entire /var is useless on most systems. But it's not a huge waste of resources either, so it's left as it is along the rest of directories under / for years. /var wasn't originally intended to be a system directory, it's just a variables directory. Almost by definition it's writable.