Use a modern filesystem like btrfs or even lvm with thin provisioning to solve that problem. Separate partitions for ease of backup, but they all pull from the same pool of storage.

I think that there's a reasonable argument for a separate home partition on a multiuser system. Means that users can't fill up root.

But a lot of systems aren't multiuser these days.

EDIT: Honestly, my biggest partitioning irritation these days is that the Debian installer makes it a pain in the rear to have a larger /boot if you're also doing an LVM-based install; the default is unreasonably small these days.

On my PC and all my home servers I keep my root partition at 10GB and haven't had any issues (although I keep everything that isn't hardware related or a system utility in home).

On my PC I crammed arch, all of KDE (+extra KDE utilities), and some other system stuff like LACT and distrobox in the 10GB root partition and run almost everything else as a flatpak installed to home.

On my servers I do the same thing but all my services are in podman containers in /opt.

Having all the software needed to make the machine work be isolated from my custom home junk makes me feel better, and I like that I can mount root as read-only to make it immutable

I have / on SSD (less writes) and /var and /home on HDD

I only do it on my ancient laptop because for some reason, it makes things a little faster. I don't know why.

Probably my installed games alone are larger than that

Yeah i never bothered with separate /home because it feels like such a balancing act to decide on size compared to root. Especially when you use nix/guix, it would be annoying to have a small root with the store filling up over time and having to do garbage collecting often. Also, i just back up whatever files i want to make sure i don't lose, and when i do a clean install i actually want everything to be wiped anyway, including home.

It's the opposite for me.