Because, that was the surname of a certain Sacred Ground Master that belonged to one of the Four Sacred Grounds in the Profound Sky Continent.
“Frozen Cloud Asgard’s Chu Yueli, has brought Senior Sister Chu Yuechan, disciples Shui Wushuang, Wu Xuexin, Xia Qingyue to visit Heavenly Sword Villa and also sends our Mistress’ regards on her behalf to Villa Master Ling and Villa Mistress Ling.” Facing Ling Yuefeng and Xuanyun Yufeng who were welcoming guests, Chu Yueli stood at the very front and slightly bowed towards the coupled surnamed Ling.