Is Descent: Champions set in Oriath?

I have tried racing in Path of Exile after a year-long break and was stunned to see Descent: Champions. Before, Descent had locations such as the Heart of Phrecia, so it was likely set in Wraeclast. Now, Descent: Champions has Gravicius welcoming contenders and a lot of NPCs (Nessa to Oak to Fairgraves to Hargan) standing in the cheering mob of people at the back of the starting area. Seems like Descent: Champions is set in Oriath, but do we have any confirmation on that from Grinding Gear?

This strikes me as strange: why would you have a hall full of monsters to feed on unlucky contenders in the middle of your capital city? Nuke it from orbit / seal it if you can't. Instead, they are letting adventurers in.

Should I, out-of-universe, think that Descent: Champions is just a race and is not really related to the main game storyline?