That's why judging is based on the ADGA scorecard.

@Goat Whisperer , there you are! I have been searching for you and SBC. Why did you leave? Baymule says to tell you that you and SBC are missed as well. I have been searching for posts from y'all on BYH and find nothing. How is Rue? I was looking forward to this year's kid posts and pictures. Is SBC on here? If so she must have changed her name like I did.
Having won BSDIS, BJDIS, and BUIS with my Nigerians, I HIGHLY disagree.
I should mention, these shows are rather large shows, several with 600+ goats entered with herds that have produced National Champions.
I worked my rear-end off to get where I am at. ADGA has a unified scorecard. All the breeds are judged with this scorecard. I can tell you; the Nigerian breed has had nothing handed to them.
Since ALL the goats are judges against the unified scorecard, why should my doe not be eligible to compete for BIS? The Nigerian breed has grown leaps and bounds. I have seen herds make more progress in a short period than standard breeders who have been at it 20+ years.
Of course the majority of the other breeds will out-milk a Nigerian. I will not argue that.
However, if that is your criteria shouldn't Saanens win every BIS? The are the most productive breed after all. I have seen a many does with horribly attached udders from carrying too much milk. Your best udder is not necessarily the one that produces the most milk. I can't remember the last time I've seen a 11 year old Saanen in the ring. I have seen some spectacular Nigerians in the ring at that age, some even winning BIS. I have also seen Nubians sweep the show ring. Absolutely stunning animals. However I've also seen milk records of these animals only producing 7# of milk a day. Production records are important.
Lets not forget that it's been shown that Nigerians tend to have a lower SCC than the larger breeds. Hypercalcemia, toxemia/ketosis are also far rarer in Nigerians VS the larger breeds.
Every breed is different and has its advantages and disadvantages. The Nigerian Dwarf breeders have done a remarkable job, even well renowned judges have said the same thing. Yes, there are some issues right now but I can assure you it is not a representation of the breed. If people think Nigerians are the only breed with DNA issues popping up, they are lying to themselves. The other breeds tend to have a quieter crowd and honestly it's easier for a "breeder" to refund a $500 goat than a $5000 goat.