Looking at the statement at the beginning
> and it only requires you to package your workload as a Docker image, which seems like a reasonable price to pay.
is no longer true as you continue down the path, since it actually requires you to do a lot more than you'd think.
And yes, you're right, all these things are complex in any situation, except when you simply use a load balancer and two servers. There are companies estimated to be worth close to US$2B using with sub 30 servers using a service you may have heard of: Stack Overflow (https://nickcraver.com/blog/2016/03/29/stack-overflow-the-ha... && https://nickcraver.com/blog/2016/05/03/stack-overflow-how-we...).
(As an aside: K8s does not free you from your Cloud vendor - after floating around my city working on various "platforms", all locked in due to IAM, for example.)
How does that simplify or solve any of the problems you mention? As far as I can see they're just as present and just as complex when you have two servers as when you have hundreds.