Emrakul, AT and Griselbrand are not as powerful in our format as they are in other formats. Legendary creatures just don’t have the impact here as they do in other formats. We’ve seen this in the form of “prime time”(not legendary) being legal here and not breaking the format. I don’t find creatures threatening non recurring creatures and legendary creatures especially see Karakas if you don’t understand what I mean. Actually I’m more concerned with mindslaver (actually it’s banned at my table) than creatures.