Why would the chain stop without a hard fork?
Because it is vulnerable to the year 2038 problem, and also to the year 2106 problem, if 2038 will not stop it:
https://bitcointalk.org/index.php?topic=5365359.msg58166985#msg58166985And why should the bitcoin community do useless hard forks for no reason?
There is a reason: four bytes may be not enough to measure time accurately. But even if it is, then taking modulo 2^32 will be also a hard fork. And if you don't want to solve that problem in the hard fork way, then the soft fork way may be too crazy to reach consensus.
I don’t get the point, it’s already possible to run pruned nodes so no need to castrate the whole chain.
It's about the initial chain download. It should be faster. A lot faster. For now, it can take many days, and that should be improved somehow.
But what point would deleting the chain serve and how would it work in practice?
The point is to make the chain smaller. And the way is to do deep chain reorganization, that will reach consensus, because the new chain could contain the hash of the old chain. When it comes to removing data, chain reorganization is the only operation that can be used to make it.
No one will agree to this, if you don’t believe me, try it and see how many nodes would follow.
In Segwit, people agreed to put signatures in a separate space called "witness". Why do you think they won't agree to put the whole chain in a separate space (called "archive"?).
Of course, stwenhao is smarter than everyone else
We all know that I am not "smarter" in any way. There are only ideas, people can always reject them. I think reaching consensus is always needed, but for some things mentioned here, I think it could be possible to do so. Bitcoin users are different, not all of them are happy about Proof of Work. Another story is that implementing some of my ideas may sound crazy, but it may turn out to be better than creating another altcoin.