You mention “POW forks”, but Bitcoin’s POW has never been hard forked: you’d need to trust a Bitcoin expert to tell you if it was a good idea.
And with proof of work a lawsuit could force the distributor to change the consensus rule so that a particular transaction is invalid - just as Ethereum did voluntarily with the original DAO.
> You mention “POW forks”, but Bitcoin’s POW has never been hard forked
Instead it’s been soft forked, which turns the consensus rules into a popularity contest. If a soft fork produces two competing branches of the blockchain, old clients will go with whichever branch has more mining power. Which means you open yourself up to interesting attacks like convincing 51% to literally steal the funds of the other 49% (which is much worse than a mere double spend). Or, more realistically, in the case of a contentious soft fork that ends up roughly fifty-fifty, you could ‘just’ end up on a different side of the fork from the people you want to transact with. Either way, soft forks don’t make the downsides of policy changes go away.
Soft forks don't force you to download and run new clients just to be able to use the network, which is an important difference. You can use your existing client, you just don't have the new features and don't run validations on them.
The greatest risk on soft forks is that chain split you mention. That's why any reasonable soft fork deployment requires a long time window with a large majority of hashrate signaling support (like 95%).
In Proof of Work, a lawsuit could force the distributor of the software to hard-code a transaction that reverses the coin theft. But in both the PoS case and the PoW case, anyone using that client would be partitioned off from the honest network majority.
> You mention “POW forks”, but Bitcoin’s POW has never been hard forked: you’d need to trust a Bitcoin expert to tell you if it was a good idea.
Bitcoin's PoW forked in 2013, when a database upgrade to the software made it incompatible between two recent versions. The Bitcoin developers had to jump in and tell people which PoW fork to follow and which one to abandon.