[DennisP]

There was a huge debate over it, and in the end everybody got to run whichever version of the protocol they preferred. Both chains still exist today, but most of the ecosystem went with the one that made the change, so that one accumulated a lot more value.

[moralestapia]

>but most of the ecosystem went with the one that made the change

with the one they were told to by the de facto authority of the Ethereum world, FTFY