Do Wiki Mass Effect :
The Asari arose on Thessia, a rich world with abundant quantities of element zero that caused much of life on Thessia to exhibit biotic tendencies. Instrumental to the rise of asari civilization was the intervention of the Protheans. Upon discovering the asari, the Protheans crafted the guise of Athame, a benevolent goddess who imparted gifts of wisdom to the asari through her guides Janiri and Lucen, a deception that allowed the Protheans to rapidly accelerate asari development. The Protheans also genetically altered the asari to grant them biotic capabilities, and defended Thessia from an asteroid strike and the resource-hungry oravores.
When the Protheans departed, they left a single beacon on Thessia, around which the asari later built a lavish temple devoted to Athame. This beacon contained Vendetta, a Prothean VI, and over the following centuries was the source of countless technological advances that allowed the asari to eventually become the most powerful race in the galaxy. The beacon's existence became a closely-held state secret, as its revelation would have discredited the virtually universal belief that the asari attained such heights on their own merit. By 2183 CE, few outside the highest echelons of the asari government were aware of the part the Protheans played in asari history.
Como os Protheans já estavam usando a tecnologia Mass Effect, é natural que eles apresentassem essa tecnologia para eles.