No court anywhere is going to get all the way to discovery in a case without representation, that's silly. If you're really in a situation where you're sued by Real Lawyers and refuse to respond like that, what will end up happening is some kind of default judgement. Discovery only happens once people start arguing about stuff.

Though there is a corrolary: occasionally you'll see suits filed against John/Jane Doe defendants. The plaintiff knows they've been wronged and wants justice, but they don't know who the entities are they need to sue for some reason. In those circumstances you can get subpoenas issued to produce e.g. phone logs or security footage, etc... in order to move the case along.