Ramban answers that Aharon’s personal kaparah was the first step toward his being able to serve as an agent to bring korbanos on behalf of the tzibur. “V’chapeir b’adcha” is a precondition to “u’b’ad ha’am.”
I want to echo and add to the sentiments expressed here. We all have opinions about why what that other group is doing is wrong and misguided and we of course are all motivated l’shem shamayim, because if only those guys would shape up, then shalom al yisrael and the world would be a better place. But there is a precondition to working “b’ad ha’am,” and that is the “chapeir b’adcha.” Start with yourself first. Whether the word open, modern, or ultra appears before the flavor of orthodoxy you align yourself with, there is work to do in your own backyard.