To be fair, "old hardware" is kind of frozen in time by definition. DSL is what it is. If you want to play with hardware with 32mb of ram, it does what it does. It isn't really an OS you want to "use" or "expand upon". I would not suggest to connect it to the Internet or expect any kind of updates, security or otherwise.

The main case for it at this point is retro computing. Most retro computing enthusiasts run era correct OS (MacOS7-9, Mac OS X, Win9x, DOS, AIX/IRIX/SunOS/HPUX, BeOS, Amiga 3x, etc). Those are not getting security updates either.

I put it in the same category as Haiku, Visopsys, AROS and ReactOS, fun toy for older computers. Not very relevant as day-to-day. I still have and expand a collection of live CDs for the P3/PR era laptop. Again, those don't get security updates, but are fun to explore.

Personally, I am more into Linux window managers (and AwesomeWM maintainer) to recreate the interesting concepts from those OS rather than rice 90s silicon. However I really enjoyed using a Pentium1 laptop full time for a few months in university in the late 00's just to prove a point. But for that I compiled my own OS rather than use a distro. If you want to get the most out of these machine, that's the way.