Articles use a more business-like tone than Posts, which belong to a Blog. A business site can have a News section where it publishes Articles.
When we have created sites for News organizations they did not like the term "Articles"; they always wanted us to call them "Stories."
So I would suggest the name be configurable, and/or the blog post subsystem extracted into a plugin so that site could implement both Articles and Stories (or any other name) and still get all the blog post semantics.
I think both Articles and Stories sound better than Posts. No strong feeling on it. I've been "configuring" the labels with a few lines of code, as needed.
Making them editable sounds good to, I have changed the title to reflect that.
Can we work on a filter hook for this? I think it is a good implementation for backward compatibility.
I have made a PR with proof of concept here.
Link to PR: https://github.com/ClassicPress/ClassicPress/pull/425
Looking on internet it is possible easily in wordpress to change any post type label also for posts: https://wpbeaches.com/change-the-wordpress-post-type-name-to-something-else/So I don't think that add a specific filter for this use case is very helpful because affect only one post type.
I didn't think about this until I saw the exploratory PR, but the only way to do this is to require the user to input all of the related "post type label" strings. Otherwise you break translations.
Given that, I think this is plugin territory. Daniele's link is a good one, there are just 2 things I would change about that code snippet:
__( 'string', 'plugin-slug' )