Beyond that, access to logins enables buying things on Amazon, sending emails to everyone you know, registering domain names and spinning up servers, stock trading, etc.
When a couple thousand dollars worth of perishable food shows up on your doorstep, what then? Not everything on amazon can be returned.
If not: still better than giving ai your password vault. I’m not saying it is a good idea to let ai buy from Amazon. I am saying that giving ai access to your password vault is still a superset of letting ai buy from Amazon.
It could change LinkedIn to add competitive work.
It could sign a married person up for dating sites and invite people to your house.
It could lie on your taxes.
It could attempt to join a terrorist movement or elicit other illegal activity on your behalf.
It could find many other creative ways to ruin your life and/or reputation, in the same brute-force manner as recent cybersecurity issues that previously would have required impossibly large teams of people.
Even if burning through cash is the only problem you care about, though, credit cards on Amazon is a small part of the financial picture for many people. Banks and brokers can be a much bigger issue.
People have wildly different risk calculators.