Most people will use LVM+Ext4 in the enterprise for backups and easy resizing and the like. Also Guix has rollbacks for the whole package manager and system so whole backups aren't mandatory, the data would be handled and backed up externally with some LVM volume, for sure there's a Guix service for backups.

Well, yeah, but in the enterprise world, the infrastructure is often really pathetic, layers of legacy garbage with "do not touch, if it breaks everything is lost" labels. I wouldn't take them as a model, which is one of the common and self‑harming behaviors many people practice: trying to imitate others just because they're big, not because it makes technical sense.

The system can be regenerated, sure, but it might fail to rebuild at some point because of a broken upstream package; that's what backups are for, and it's handy to have them for everything. Adding, say, thirty gigabytes for the system costs little.

LVM does allow you to operate, yes, but with much heavier limitations and far more inconvenience than ZFS... And here we come back to operations vs. even top developers, like Andrew Morton's infamous quote about ZFS, which shows the difference between those who genuinely manage complex systems and those who only see their own workstation and don't understand broader needs to the point of denying they exist even for themselves.