Why is the query string from the Chat auth flow returned with a hash (#) instead of a question mark?

Why is the query string from the Chat auth flow returned to my callback URL with a hash (#) instead of a question mark? As anyone who develops enterprise level software should know, everything after # in the URL will be ignored by the server, so redirecting to a backend script means the query string cannot be parsed. What were you guys thinking?

Look at the response sent to the redirect uri here: https://support.zendesk.com/hc/en-us/articles/4408828740762-Chat-API-tutorial-Generating-an-OAuth-token-integrated-Chat-accounts-