You are providing the truth but with wrong example.
The discussion about which one is the real bitcoin chain is fairly simple, the one decided by (majority of miners). That's the only and valid reason.
No, miners must comply with Bitcoin's consensus rules, which are enforced by all full nodes on the network.
For example, miners could begin mining a chain that inflates mining rewards beyond 21M bitcoins. The network of full nodes, however, would ignore that hard forked chain as invalid and the mining rewards would be worthless. So, miners will only build on a chain that the Bitcoin network accepts as valid.
Bitcoincash miners came together to undo an profit made by an attacker. It's not just a miner but all miners in two of it's largest pools. They did it because they were sure it's for the good of Bitcoincash. It does not mean bitcoincash is centralised.
Effectively, it was done by two pool
administrators who used their collective hash power to 51% attack Bitcoin Cash to reverse previous transactions. This does suggest Bitcoin Cash is pretty centralized since it took very little coordination to successfully attack the chain.
