Why does Riot pick on Azir when Xerath exists?

Riot talks about Azir being nerfed and unhealthy because his range is too much and lacks counterplay but Xerath is supposed to be healthy? Or is this one of those cases of "one was played in lcs and one wasn't?"

Xerath has 340 base movement speed which is among the fastest of any mage in the game so calling him immobile is not true. With boots and a luden's echo his movement speed goes up to 419. He has a stun that moves at 2300 speed and his passive allows him to legit spam you out of lane unless you're hyper mobile. If Azir tried spamming people out of lane like Xerath does at earlier levels he would oom and be forced to last hit everything in closer proximity allowing his opponent to poke him hard but nope not Xerath.

Before you present the argument of "Well Xerath takes skill to play him like that" do you really think Azir doesn't? The fact of the matter is a great Xerath player has almost no counterplay in lane unless you're playing a handful of very specific champions. His range is so great that ganking him is rarely possible as well.