One other thought.
The need for permalink in date arises from date needed in filename. Here’s why.
If you didn’t have the file name restriction then you have to keep track of names yourself by adding your own identifier to satisfy your IDE or shell.
Because at the file level, they can’t both be hello.md.
And then you would have got URLs as
That is how blog posts could have ended up and still have no risk of duplicates!
I mean that’s how non blog posts work.
But… because we do have Jekyll setting date as required in post names, you must do this
That alone would mean both output as /hello.html and collide as duplicates.
So as a consequence, we must put date in the permalink for posts, for most cases.
To safely get.