We use Stripe for our payment processor. Stripe requires that we confirm the identification of the person who will receive the funds for your event.
Stripe is required by our financial partners and KYC (Know Your Customer) regulations to ensure that there is a real, verifiable person behind each account. This is the same process for small mom and pop shops to even Fortune 400 companies.
Unless we have this information, our financial partners would eventually prevent us from sending payouts to the account until the personal details have been verified.
This link has more information: https://support.stripe.com/questions/why-do-you-need-my-date-of-birth-and-4-digits-of-my-social-security-number