Server Action Library Question - When Would I Use $_GET/POST?

I’m just learning how the new Server Side Library Actions work. Thanks for implementing them guys, they are really exciting!

A question. When I define a Library Action I can give it $_GET and $_POST variables. What is the use case for these?

I can see that with a exec library action, everything comes in through $_PARAM. So I’m guessing that $_GET/POST has no use case here?

With an include library action, do the $_GET/POST variables get added to the existing ones already defined on the server action I include it from?