I strongly believe it's the ease of use factor. If you know nothing at all about containers, but have just installed docker, you can immediately "docker run htt

I strongly believe it's the ease of use factor. If you know nothing at all about containers, but have just installed docker, you can immediately "docker run httpd" and watch a web server install itself and do something useful in seconds. That's really powerful, and the surprisingly diverse selection of pre-built containers on the docket hub makes it even easier to bootstrap your project and figure the details out later. I don't have the necessary expertise to compare it meaningfully to other container systems so I can't speak to it's implementation details, but the first time user experience is more than enough to explain it's popularity.