Even the current centralized ICANN flavor could be substantially more resilient if it instead handed out key fingerprints and semi-permanent addresses when queried. That way it would only ever need to be used as a fallback when the previously queried information failed to resolve.
Think about what would happen the day that letsencrypt is borken for whatever reason technical or like having a retarded US leader and being located in the wrong country. Taken into account the push of letsencrypt with major web browsers to restrict certificate validities for short periods like only a few days...
I haven't followed this closely, but have there been any... shall we say plain outages longer than six hours? That's not an outrageous TTL. Or a day.
If Let's Encrypt goes down, half of the Internet will become inaccessible in a week.
* https://www.keyfactor.com/blog/2023s-biggest-certificate-out...