The Echo allows one to ignore the effects of tempering. That is part of why the Scions rely on the Warrior of Light to deal with primal threats. It is possible to defeat primals without fighters who have the Echo, but it tends to be rather messy. For example, the Company of Heroes had to rely on a three wave system, the first getting tempered, the second killing the tempered, and the third defeating the primal. Similarly, Immortal Flames expeditions to fight Ifrit are said to lead to large amounts of tempered Casualties. In 1.0, all of the members of the Path of the Twelve had the echo. In 2.0 onwards, but it can be assumed that your companions are adventurers with the echo.

Several characters with the echo (it's artificial form) have used it more creatively though. Ysale and Zenos managed to use their echo-given resistance to control primals. When Garuda, Shinryu, Ifrit, and Lakshmi all attempt to temper the player character, they are shocked by it not working.