It's just like everybody was fighting using holy hand grenades and somebody came into the game with a nuclear bomb. Technology upgrades did happen quite a few times in history.

The difference is that in real life, who came up with new technology gradually own the entire system, so they then became the maintainer of the system, not breaking it. In Bitcoin/altcoins, PoW miners with new technology will not be able to out-rich Satoshi, so they keep breaking the network until they feel satisfied.