How does this work? I don’t fully understand the process here

Check out the custom feeds. My Feeds -> Settings Cog -> Discover New Feeds. It's like Twitter trending if the algorithms could be written by users instead. It opens this place up a LOT.

Essentially you sue the company claiming to own your debt and say “show me the paper” and when they can’t or don’t show up in court you are awarded a default judgement

If the shell company can’t prove it owns your particular loan because it either lost or failed to keep specific records, you can have your loan dismissed. I believe this can be done with a lot of medical debt that has ended up with collection agencies too. (Not a lawyer.)