Also having everything system specific live under a single path means easy backups, easy immutable trees that can be A/B swapped for seamless and online updates with easy rollbacks.
No more wondering where the various tools live since everything lives in /usr/bin and more.
The original point of a non-merged /bin (and /sbin) was to contain essential binaries for system recovery and early boot, that should be available even when a separate /usr/ partition is not yet mounted. Keep in mind that the approach of booting from initrd is quite non-idiomatic and used only for convenience wrt. a generic distro install; you're generally meant to recompile your kernel so that it can mount / directly at boot and find everything it needs there, without requiring to mount either a ramdisk or a separate partition. This means that early-boot stuff must live there in order to get the benefits of separate partitions in the first place.
> The original point of a non-merged /bin (and /sbin) was to contain essential binaries for system recovery and early boot, that should be available even when a separate /usr/ partition is not yet mounted.
The original point of a non-merged /bin was that /usr/bin was a spillover from when they ran out of space on the primary drive back in the 70s, so there was a slapdash split where the stuff necessary for bringup was kept in /bin and the rest would be kicked down to /usr/bin, in a very inconsistent manner depending on the system’s evolution.
In fact that’s also why users were moved from /usr (the original location, hence the name) to /home: /usr ran out of space, so they added a third disk and moved the user directories over there.
> Keep in mind that the approach of booting from initrd is quite non-idiomatic
How can you claim that it’s non-idiomatic when it’s the standard approach?
You still need an initramfs in the case your bootloader/kernel doesn't support your filesystem; for eg GRUB didn't support LUKS2 and the Linux kernel can't boot LUKS directly without userspace tools to input the passphrase etc.
Your distribution needs an initramfs for that reason; you as a user can just recompile the kernel so that the modules it needs are built-in rather than needing to be loaded separately from a ram-disk. If you need an early-boot file system at all (as with an encrypted /), it can be provided in /boot/ and then "swap root" to / at boot like initrd does.
Nowadays a network files protocol fits inside the system initializing ROM, so all of those old issues are moot and we have completely different problems to optimize for.
Also having everything system specific live under a single path means easy backups, easy immutable trees that can be A/B swapped for seamless and online updates with easy rollbacks.
No more wondering where the various tools live since everything lives in /usr/bin and more.