Lots of people here are using Namecheap for their domain registration, so I hope this incident wakes them up and makes them move their domains to somewhere safer!
As someone who has a number of domains under Namecheap, I find this alarming; they're an industry giant. This thing should not happen to any of their client. I would have to ask support personally about this issue because if your domain can be transferred by a simple phone call, what would stop scammers from stealing your domain?
This all could've been prevented by strong multi-factor authentication, so this wouleve definitely stopped the take over as long as the unauthorized party doesn't have access to the security keys.
They have a strict transfer protocol that takes days to complete; I believe the protocol was not followed, and Namecheap could be responsible for this.
Shortly after order submission, the transfer gets initiated at the Registry, and the domain acquires 'pendingTransfer' status. Transfers that have reached this stage are automatically confirmed within 5 days. Finally, it may take additional 24-48 hours for the Registry to complete the transfer.
How to Transfer a Domain