I more view it as us recognizing that there's more to "a system" than a binary. Kubernetes is this concept taken to its conclusion (since it defines everything in code, literally everything). But docker is often a super convenient middle ground where it's not nearly as stupidly verbose to just get a simple thing running, but still checks a lot of the boxes.
I used to feel similarly with Java. "Why," I asked, "would you need this docker thing? Just build the shaded JAR and off you go."
And to be sure, there are some systems - especially the kind people seem to build in go (network-only APIs that never touch the fs and use few libraries) - that do not need much more than their binary to work. But what of systems that call other CLI utilities? What of systems that create data locally that you'd like to scoot around or back up?
Eventually nearly every system grows at least a few weird little things you need to do to set it up and make it comfy. Docker accommodates that.
I do think there's a big kernel of truth to your sentiment though - I loved rails as a framework but hated, just hated deploying it, especially if you wanted 2 sites to share a linux box. Maybe I was just bad at it but it was really easy to break BOTH sites. Docker has totally solved this problem. Same for python stuff.
I do think docker is also useful as a way to make deploying ~anything all look exactly the same. "Pull image, run container with these args". I actually think this is what I like the most about it - I wrote my own thing with the python docker SDK, basically a shitty puppet/ansible, except it's shitty in the exact way I want it to be. And this has been the best side effect - I pay very little in resource overhead and suddenly now all my software uses the exact same deployment system.