But what's important is that it's all rock solid and 100% reliable, because none of it leaves my house. I don't have any "cloud" crap. Everything exists on my local network only. Well, that's not totally true. I have a Nest thermostat. It's the only device that ever gives me trouble, and it took a whole day to get automated. Some day I'll replace it.
I'd argue that your plant timer is reliable not because it's old and not networked, but because it doesn't have dependencies on servers thousands of miles away and isn't reliant on the continuing goodwill, solvency and work ethic of the company that sold it to you.