I think it's one of the two biggest reasons. The other, possibly bigger, reason is that it gives you a way to install fairly complex software and have it reason

I think it's one of the two biggest reasons. The other, possibly bigger, reason is that it gives you a way to install fairly complex software and have it reasonably configured and running right out of the box. I use Docker to run stuff like PostgreSQL on my dev box. Not so much because it's a technically superior option (in truth, it's slower and eats more memory than installing it directly on my machine) as much as because it reliably lets me get up and running in a few minutes, just the time it takes to download the image, really. All the other options I've tried invariably require some fiddling, especially if you need an older version. I suspect that all the other codepoints that have ever been spilled on the subject are mostly just an attempt to get ops on board with it. (Disclaimer: All above comments are a mix of wild speculation and Freudian projection. I tend to come down against using it in production.)