Ah the SMB alternative. Okay yes I’m familiar with that.

Unfortunately it was still frequently in use 10 years ago on Apple systems (particularly the time capsule which was only discontinued in 2018) , and there are derivatives in use today. So I’m not sure it’s an apt comparison point.

The Wikipedia article actually links to implementations like netatalk that have updates as recently as a couple months ago. So it is actively maintained beyond what ReiserFS has.

netatalk and AFS are similar but truly not the same, netatalk in linux does not afaik have an actual kernel driver.

AFS however, does, and I was doing MacOS sysadmin work in 2011 and it was strongly discouraged to use anything other than SMB, which frustrated me because samba3 was a pain and I considered SMB a windows technology at the time.

The time capsule as you mention also discontinued the usage of AFS after the first version (I actually have 3 at home right now still, a 1st gen, 2nd gen and last gen - the tall one).

AFS's use today, not sure, but as mentioned, 13 years ago at least it was strongly discourage by Apple themselves.

AFP was still the default though in 2012. And even though you weren’t able to provision new time capsules to communicate over AFP, it was still supported.

I’d bet there’s a significantly larger set of devices active at any given time during the existence of ReiserFS to today that still use AFP.

And I’ll point to https://news.ycombinator.com/item?id=42101313 that says AFP has no kernel support, but something else called Andrew File System does.

Well, the "simple, incomplete" Andrew Filesystem is actually an even better example then, as it cannot possibly have users as it's incomplete but has been in Linux since 2004.