Why do people always refer Beyonce as the Queen or treat her as one?

Because she is currently the most popular female R&B artist, selling the most records, doing the most tours, and HAS been in the game for a significant amount of time. Usually when people refer to her as the Queen, they mean "the Queen of R&B". Although there are other women in R&B who achieved more success than Beyonce, they aren't currently on such a fire streak like Beyonce is. Beyonce embodies all aspects of R&B, she has a huge, wide-sweeping fan base, she just is so BIG worldwide, how could she not be considered to be something special? She is extremely famous.