I was running Debian unstable on my 64-bit SPARC up until I moved a few months ago and haven't set the system back up again while unpacking.

It's been somewhat useful for finding weird edge cases in software where for whatever reason, it doesn't reproduce easily on AArch64 or x86, but does there. (Or vice-versa, sometimes.)

I don't know that I'd say that's sufficient reason to motivate dozens of people to maintain support, but it's not purely academic entertainment or nostalgia, for that.