It's not necessary to have the Echo to face a Primal. What is a necessity a strong will and mind. Speaking of Zurvan, you'd recall that several of the troops present fell to his influence, but others did not. Strong willed individuals such as this likely composed the Company of Heroes, who I doubt all had the Echo.
That is because there are two forms of Tempering that we saw. One is like with Zurvan - unintentional. The second, as we see with Garuda and Ifrit, is very much something the Primal actively performs. So long as this second is not done, people even without the Echo or the Blessings can fight a Primal without falling under their influence. Those are likely most of your companions.
Then there's also examples like what happened when the Mothercrystal protected us from Ultima - she protected our allies as well. While to a lesser degree, I believe our party members receive protection from Hydaelyn by virtue of association with us.