I guess people have been super lucky with legendaries from emissaries with all this talk about saving them or what not. I have been doing emissary quest every day since expansion launch and has not received a single legendary from emissary. Every legendary i have gotten on any character is from either mythic+ cache or raid bosses.
But regardless, ppl have already been getting the new legendaries since 7.1.5 so is no reason to wait till nighthold opens to get them.