Many of us have a handful of Pis at home doing whatever they do, each with their own unique MicroSD card. In this configuration, every time the number of Pis doubles, the overall MTBF for their collective storage halves. Backups are a pain since each Pi is a unique and special snowflake, and are thus somewhat unlikely to actually get accomplished. When a MicroSD card does die, that Pi's configuration and all of the work that went into making it do whatever it likely disappears with it.

However, when booting over the network:

A handful of Pis are at home doing whatever they do, and booting from a reasonably-resilient NAS (eg a ZFS RAIDZ2 box) somewhere in the house (which is a great idea to have around for all kinds of other reasons, too). Adding more Pis does not decrease storage MTBF at all, since there is no MicroSD card to die. Backups become simple, since ZFS snapshots make that kind of thing easy even if each Pi's disk image is a unique and special snowflake. Space-efficient periodic snapshots become achievable, making it easy to unfuck a botched change -- just roll back to an hour ago or yesterday or whenever things last worked and by using that snapshot instead. Undetected bitrot becomes zero. Speeds (for many workloads) might even increase, since at least the Pi4 can handle wire-speed network traffic without any real sweat.

It's not a great fit for everyone, but it may result in a net long-term time savings for some of us folks here who tinker with stuff at home if enough steps are automated, and it seems likely to result in fewer frustrating surprises.