I want to know the answer to the following question:
Why are Dzongkha, Sikkimese, Sherpa, and Ladakhi considered to be separate languages?
All the background I'm provided with is that "However, if the latter group of Tibetan-type languages are included in the calculation, then 'greater Tibetan' is spoken by approximately 6 million people across the Tibetan Plateau.". Is that enough to answer the question?