Instead of learning docker itself, look for a project you really like that offers a docker-based install and deploy that. It'll usually take less than 20 lines of terminal commands. It's a good start that gets you to feel the usefulness of docker, and the basics that you'll need for most deploys.

It doesn't need to completely replace the current platforms. The beauty of the decentralized internet is that platforms suddenly disappearing/dying wouldn't mean we lose years or decades of information that was contained in that site/forum/corporate entity.

Decentralization would also encourage a lot of people to go back to blogging, which would mean information would come from all over the web again.