If it is known as ETH then it is the main chain, not the fork.

Right. That's my point. Even though ETH hard forked to undo transaction history, the fork is still considered "ETH" because that is what the leaders decided (and the community agreed to that decision). If Vitalik had made a different decision then the "ETC" chain would still be called "ETH" today.

whats missing here I think is the value of social consensus. None of these coins have any staying power without the social consensus that makes them the main chain. Its why there can't be clones with the same value popping up every day, there is clout that the dominant chains maintain