It can be a bit cumbersome to manually scroll to the bottom of an article to be able to reach the linear navigation bar and use its links to go to the previous article, the next article, or the containing article or category. Please add a global option or an option for each individual article to include a duplicate linear navigation bar at the top of a world's articles so we do not need to scroll to the bottom of each article to use these links if this option is enabled.
I imagine that this may not look that good as it would be added to the top of the page, which is why even though I'd use it for all my articles, I'd want it to remain an option that needs to be enabled.
I would probably never use this feature, but I also get that it could be useful in certain situations to have one at the top. As long as this remains something you would have to enable manually, I don't have anything against it.
Navigation is at the bottom of an article because people generally read the article before navigating away from it. However, in cases like a sequence of plots or session reports, having a link to the preceding article at the top of the page also makes a lot of sense. There are simple alternatives like breadcrumbs in the global article intro or a mention link at the top of the vignette, but I see the appeal of a system that more directly supports sequential articles.
Interesting, I think this needs to be thought through a bit more. But you can do all of this manually, using the mention system.