You're correct that it's a last resort, but its primary role is to, literally,
charge back to the original merchant. "[letting] the processor know that their customer isn't holding up to their end of the agreement" is a side benefit. As is eventually dropping the merchant when there are too many chargebacks to justify supporting them.
> Through a chargeback, your bank can try to get your money back from the seller on your behalf it isn’t a legal right, but your bank is committed to helping you, and will treat any claim fairly.
https://www.visa.co.uk/how-you-pay-matters/chargeback-purcha...
> When a customer disputes a debit or credit card transaction, the card issuer must determine whether to provide that cardholder with a refund for the transaction amount—also known as a chargeback.
https://b2b.mastercard.com/news-and-insights/blog/what-is-a-...
> A chargeback is a rules-based mechanism, with time-sensitive workflows, that enables the issuer and the acquirer to determine the financial liability of a disputed transaction.
https://www.mastercard.us/content/dam/public/mastercardcom/n...
> A chargeback occurs when, after investigation of the dispute, we debit your account for the amount of the disputed transaction and credit the Card Member with this amount.
https://www.americanexpress.com/au/merchant/chargebacks-and-...
Notice none of them talk about it being a feedback mechanism. Because it's not. It's a refund mechanism used as a last resort.
