Containerization has obviously been around for ages before Docker came on the scene, yet it's adoption has dwarfed that of other similar solutions, why is that?

People have to start with a technology somewhere, if they get frustrated with the process, often they'll discount it and move on, that first moment of success of "ohh that was easy" is really important.

Docker has that. Sure it hides a wide variety of complexity under the skin that, in more complex deployments, can come back and bite you , but for people getting started it's much easier than the alternatives.

The "App store" like nature of Docker Hub is another part of that, the ability to easily find base images that you can use to prototype solutions is super-useful as a beginner.

Of course once you've been using it a while, you might have questions about image provenance, vulnerability management etc, but those typically aren't part of the initial evaluation.