By your argument, black people are not the most disadvantaged. All the smaller groups are who make up a smaller proportion of the population.
1) Nobody mentioned a single thing about black people being the most disadvantaged, nor was that ever a subject in this thread.
2) Yes, minorities often suffer various disadvantages due to being minorities. That's the broad issue.
Privilege just determines where people are advantaged and disadvantaged in comparison. Again, it does not make a blame judgment on anyone in itself.
From that point, you try to determine the causes and see if those advantages/disadvantages can be evened out over time, because, if you're not selfish, you don't want to be advantaged over another human being in many aspects of life if at all possible.
Using dating, as an example, knowing how hard it is to find someone compatable in the first place, we shouldn't want people to have to work with 15% of the pool they're already working with if at all possible, so we can look at things like the science of attraction (specific attractors are learned behaviors, imprints are set when you're in developmental phases) to see if there's anything that society is doing to affect people's attractors (for instance, presenting Asian men as non sexual beings, but sidekicks and nerds in most media for years and years may have an effect on how "sexual" they are viewed in broad majorites of adults now).
Privilege needs to be pointed out only because so many people in a position of advantage refuse to see the advantages they have. As a male, there are still a TON of things I don't consider about what a woman deals with, for instance. Or being tall, or having the use of all of my limbs. Everyone has a ton of blind spots to where they have advantages.