Why do supermarkets stupidly pay rent in Manhattan, London, LA or Singapore when they could pay next to nothing to have a store in the Outback or Siberia?
Because they want the users who are using WhatsApp, and their population is not using telegram. Business decision is about money, you go where you can make the money
They didn't say that. They said why do people pay for WhatsApp business. That implies they want a business account. That implies they went access to a certain customer base