I'm not contesting this since I'm a new player and don't know any better, but that seems absurd. What is even the point of speccing into speed/mobility & light armor then? I keep running into statements that bolster the notion of "be a warrior or go home". Does this game ultimately boil down to heavy foot fighters winning?
Maybe slightly over-exagerated. Speed works fine in shorter distances, it works fine in both short and long distance for fast warriors.
Ill give you an example.
If you are playing a sheevra mage that has 431 speed, and you are fighting a full khurite warrior that has 429 speed. If he is not already on you hitting you, he wont be catching up to you anytime soon. Now if you start running and want to leave, he will probably end up catching up to you over the course of your kiting because mages have way less stamina than warriors.
The distances it takes depends on builds, how good someone is at managing their stamina, terrain etc.