In plain terms.
The Immortal Domain wants to openly take away all the world-shaking geniuses of Nine Heavens and Ten Earths, squeeze out the last bit of potential of Nine Heavens and Ten Earths, and, at the same time, it wants to demonstrate its absolute power before them.
By doing so, it aims to highlight its supreme authority, making all the beings in Nine Heavens and Ten Earths believe that those taken away are genuinely blessed with the ultimate opportunities and grateful for the kindness of the Immortal Domain.
To put it in a not-so-appropriate way, they want to have their cake and eat it too.
Behind the old man with the goatee, a group of young boys and girls stood with their hands behind their backs, a look of arrogance intensifying on their faces as they observed the indigenous creatures of Nine Heavens and Ten Earths gathering below.
"Not even one has reached the Beheading Me Realm. This world is truly becoming more and more barren."