AWS would much rather let you accidentally overspend and then forgive it when you complain than see stories about critical infrastructure getting shut off or failing in unexpected ways due to a miscommunication in billing.
As long as "shut off" potentially includes irrecoverable data loss, I guess, as it otherwise couldn't conclusively work. Along with a bunch of warnings to prevent someone accidentally (or maliciously) enabling it on an important account.
Malicious or erroneous actor can also drop your s3 buckets. Account change has stricter permissions.
The key problem is that data loss is really bad pr which cannot be reversed. Overcharge can be reversed. In a twisted way it might even strengthen the public image, I have seen that happen elsewhere.
