It's clearly been working for decades. The only reason modern software needs so much attention is because 1) Internet connectivity requires constant security updates and 2) new features to sell, neither of which should apply here.

Does it? It sounds like this software has been doing just fine for longer than most of us here have been alive. Interesting that your preconception has not been challenged by this obvious counterexample.

The hardware is eventually going to give out, which might require a change to software, but the software itself is clearly fine and doesn't need mucking about.

Not only does this decades old software from the article tell you otherwise, but it doesn’t apply to gardens either. We (and many others here) don’t tend to most of our garden and all is fine.

There are piles of software on Archive.org from the 70s/80s that was not touched since it was built and it also works fine. Not everything is brittle always breaking tech. Not everyone is a feature hoarder either so why would you need changes to something that works well; without changes, things don’t just break.