Stripe can charge a bank account via ACH debit, but it needs a verified account and routing number first, the same thing Plaid's Auth product returns after a user links their bank through Plaid Link. Chaining the two together, verify with Plaid, charge with Stripe, has been a standard pattern for exactly that reason.
It's not the only path anymore. Stripe's own Financial Connections product lets a customer link their bank account directly within Stripe's flow, covering some of the same account-verification use case without Plaid in the stack at all, for a business that's exclusively on Stripe for payments.