There are environments and devices where automation is not possible: not everything that needs a cert is a Linux server, or a system where you can run your own code. (I initially got ACME/LE working on a previous job's F5s because it was RH underneath and so could get Dehydrate working (only needs bash, cURL, OpenSSL); not all appliances even allow that).
I'm afraid that with the 47-day mandate we'll see the return of self-signed certs, and folks will be trained to "just accept it the first time".
You linked to a whole thread in which the top comment asks a question that's a slippery slope, and of which the top answer lists advantages of a reduced validity time (while pointing out that too short like 30 seconds poses reliability and scale risks, to address the slippery slope argument).
What did you mean to point out?
For new certificate you can keep the existing amount of human oversight in place so nothing changes on that front.
With manual renewals, the cert either wouldn't get renewed and would become naturally invalid or the notification that the cert expired would prompt someone to finish the cleanup.
Many things need to be run and automated when running stuff, I don't understand what makes SSL certificates special in this.
For a hobbyist, setting up certbot or acme.sh is pretty much fire and forget. For more complex settings well… you already have this complexity to manage and therefore the people managing this complexity.
You'll need to pick a client and approve it, sure, but that's once, and that's true for any tool you already use. (edit: and nginx is getting ACME support, so you might already be using this tool)
It's not the first time I encounter them, but I really don't get the complaints. Sure, the setup may take longer. But the day to day operations are then easier.