Because at SWBTS that's the ONLY theology they consider legitimate anymore. They once did not....but it changed about 30 some years ago to complete calvinism albeit somewhat cloaked and coded by euphemisms. There were some theological "dust ups" (disagreements) over the shift as they once were more focused on historical/traditional BT instead of Calvinism. The Paul Washer types leading the charge of subject matter.
However, I noticed a change more specifically away from anthropology and language studies towards a focus on single words and theological statements.
And today, I love the anthropology and history of the time of writing the various books and letters which caused them to be written to start with. (Which tends to rub against some of their theologies today)