Peertube is run by volunteers who pay with their own money and time for the convenience of others to use it for free. People generally run it to give people social media options outside centralized corporate control.
Why would someone put themselves in legal jeopardy and host pirated content, knowing their arrest is imminent? You can’t hide your site easily.
Porn would be overwhelmingly expensive to run because of the sheer amount of traffic, storage, and numbers of people. It would have legal exposure too and require huge moderation problems, with no return for the effort.
Depends on the application for me. For Mastodon, I want to allow 12K character posts, more than 4 poll question choices, and custom themes. Can’t do it with Docker containers. For Peertube, Mobilizon, and Peertube, I use Docker containers.