A hard fork is allowed to violate existing rules, and gives you more flexibility in what can be changed. And miners do not have the power to decide whether or not a hard fork will happen. A hard fork is determined by the users, who have to upgrade their software.
If the software updates automatically, then the power of hard forking lies with the developers, who could just push the new code out via an automatic update.
The power is split but the constant "fights" between the different parties (miners/users) is the reasons these fist-gen (PoW/PoS) blockchains can not be efficient. There is and forever will be a misaligned interest between the two parties which drives up prices and slows down progress.
Software's auto-update feature is completely irrelevant to consensus. It obviously does not define who has the power at all. To update is always voluntary. Software devs dont technically have any power they have influence.
This has been demonstrated empirically numerous times in crypto history, most notably the moment that >80% of the hashrate openly supported a hardfork that subsequently failed because it did not have user support.
Your node software decides what fork you run on. If someone can push an update to your software without your consent, they can choose to put you on a fork and you may not even realize it happened. This is why most full node software (including bitcoin and Ethereum) does not support automatic updates.
This is based on the assumption that miners would rather choose to abandon their business as a matter of principle than mine on the most profitable chain, and also somehow convince any future, unaffiliated prospective miners to also do the same. How could they ever achieve that? Miners don't control where the financial incentives are.
The power is split between miners and user. A majority from both parties are required to determine where the network goes the rest are somewhat forced to follow. If no such majority can be found the network can fork and both chains can be profitable for miners. I never said miners are in control, I disagreed with the parent who said users are in control - big difference.
> A hard fork is determined by the users, who have to upgrade their software.
Who are 'the users' here? Light clients? Users of wallets? None of these have the power to adopt a fork, soft or hard. The collective action of the miners (or validators) defines which chains still retain liveness. For example in the hard fork between Ethereum Classic (ETC) and Ethereum (ETH) ETC was able to exist only because miners chose to to mine it. This in turn did give non-mining users the choice of how to distribute their demand and create extrinsic value for the ETC token. I wouldn't say this gives non-mining users any control over a hard fork since it happens after-the-fact.
> If the software updates automatically, then the power of hard forking lies with the developers
I don't know of a node distribution for Ethereum that works this way.
The core developers have power as in knowledge and power as in authority, the later being the traditional form of political power.
The ETC fork would have been successful at any non-zero support level from people with the ability to mine. And since any CPU can mine (just inefficiently), any fork can get a mining baseline. That may not give you a ton of security but it works.
People who run full nodes are the ones that decide hard forks.
> The ETC fork would have been successful at any non-zero support level from people with the ability to mine.
It would be economically irrational for people to send transactions to a fork with a single miner since that miner could unilaterally rewrite any transactions as they see fit. This is why I think miners have the ability to control forking.
Kinda funny how this problem was solved before ETH even existed simply by removing the incentive for the hardware operator. No block rewards and no fees to collect aka no reason to fight over it. The only people who run the hardware without getting paid for it are the people who want to use it. They have aligned interest like a fast and cheap network and fast update cycles. And ofc no one who has to pay for the hardware and energy has any interest in PoW.
