Paradoxically though if it failed every 1 year then pretty soon maintenance would have to be performed every few months or days or else there would be so many failures it would be really hard to ignore.
I personally achieved completely automatic renewals (https://jrock.us/posts/rotating-envoy-certs/) but it involved some work. (It also works so well that I don't even believe it. I have to go manually check from time to time because my monitoring never shows me any errors, and there are so many moving parts that I am continually amazed that everything works perfectly.)
Other people just aren't willing to do that. They like their nginx/Apache sitting on a lonely Linux box that they ssh into once every 5 years. The cost of changing any of that software is high, and they don't have a good system for running new software, like Certbot. We definitely didn't fix that.