In my WordPress example, one of the obvious reasons for using containers is simplicity. Instead of having to install all of the requirements for the world's most popular blogging platform, you can deploy it with a single command.
But there are other reasons to use containers. For example, containers make it easier to scale an application to meet demand. Say you deploy WordPress to a Docker Swarm (a cluster of Docker machines that work together). With that deployment, you could easily scale WordPress from a single node to multiple nodes to better handle higher demands placed by users.
Another great reason to use containers is for development. Let's stick with our WordPress example. Say you want to build a new WordPress site but you first want to test it on your local network before unleashing it on the public. You could quickly deploy WordPress as a container, get creative with the site, and (once you know it's ready) then deploy it for the public. Containers are absolutely great for development and testing purposes.
Although containers tend to be mostly used by businesses, I've found them to be incredibly helpful as a means to deploy very helpful applications and services on my LAN (for use by my family even). At the moment, I have containers deployed for invoicing, collaboration, productivity, and communication on my LAN. Each of these platforms was deployed quickly and easily, thanks to containers.