It seems implausible that a company of AMD's stature would risk their reputation and attempt to perpetrate a hoax on the consumer by permitting a new product to enter the marketplace without being fully tested for performance and safety.
It's not so much about performance and safety.
It's about not meeting PCI-e specifications.
You're right, I can't imagine that this would slip by an outfit the size of AMD.
Therefore, what I think happened is this:
1) They designed the PCBs for sub-150W performance, thinking this would be the ballpark, and performance-per-watt was promoted as a big selling-point for the Polaris architecture (having only a 6-pin connector gives off the impression of a card that is very power-efficient... note that nVidia's 145W GTX970 still uses 8-pin, just to be safe).
2) When the first 14nm FinFET GPUs arrived, the process was rather immature, and power consumption was considerably higher than originally expected (a similar situation to the GeForce GTX480 for example)
3) They had 2 choices: Either they'd clock the GPUs lower than intented, and they wouldn't hit their intented performance-envelope. Or, they could just jack up the GPUs so they'd have competitive performance, and pray nobody would notice/care.
It's obvious which option they took (I guess a lot was riding on them at least reaching 970/980-like performance levels, because anything lower would be viewed as a failure).
And various sites noticed.
No, your PC is not likely to melt down (although there is a reason why AMD made this driver fix... the PCI-e slot is a lot more fragile than the 6-pin connector, and the slot could indeed get damaged, especially on older boards... some people even report that this has happened), but that doesn't mean that the parts are in-spec (not meeting specifications means that they would not have the right to use the PCI-e trademark, which could mean legal consequences, as PCI-SIG would have to actively defend their trademark against any infringement). There's a big gray area between 'in spec' and 'melting down', it's called a safety margin. RX480 operates somewhere in that gray area.