We added titles to the URL for SEO purposes -- Google told us that search terms in URLs rank higher. That's why all the blogging software puts the post title in the URL.
Fun fact that, it's actually optional on reddit. You can put anything you want there and it will still work. These two are the same:
The reason we made you unable to edit titles is to avoid the bait and switch. Getting a bunch of upvotes and then changing it. If you want to say, "well how about in the first five minutes" our counterargument was, "just delete the post and make a new one". It kept the software simpler.
Besides technical reaosns, it could be to avoid bait-and-switch schemes, where a lot of engagement is built around one headline, and then it's changed to something with a completely different meaning.
I think it twitter's case it was architectural. By treating tweets as immutable the could publish them on a pipeline and not worry about duplicate copies around the system being out of sync.
Fun fact that, it's actually optional on reddit. You can put anything you want there and it will still work. These two are the same:
https://old.reddit.com/r/antiwork/comments/v3ae16/rantiwork_...
https://old.reddit.com/r/antiwork/comments/v3ae16/grayskull_...
The reason we made you unable to edit titles is to avoid the bait and switch. Getting a bunch of upvotes and then changing it. If you want to say, "well how about in the first five minutes" our counterargument was, "just delete the post and make a new one". It kept the software simpler.