Eh, aren't all FSs the same, essentially? Can't we just configure the limits during the OS installation and be done with gazillion FSs?

No, they aren't. Especially not distributed filesystems which really aren't yet a "solved problem", which in part explains why there are all these proprietary competing ones still around and companies everywhere using all different ones. NFS, BeeGFS, Weka, Ceph, Lustre, GPFS, GoogleFS, Coda/AFS, and more, each with their own flavor of crap.

For local filesystems, the average PC user shouldn't really care though. Just use whatever your installer defaults. But this story is about a distributed filesystem.

I don't have great hopes for one capable of such massive scale being good and usable (low overhead, low complexity, low adminst cost) in very small configurations, but we can always hope.

There’s definitely a space for these highly-specialised filesystems. You wouldn’t want to use this as your /home FS, nor would you want to use ext4 or something similar for what they’re trying to do.