It’s not that it’s not possible to use /assets as the root folder for links to local files, but then you would need to explain to users that there is a (Unix) syntax to go up of one level in links and that they can use that every time they want to refer to something outside the default folder:
../../another-folder/example.png
What’s really missing is a way to change the default behavior when adding new asset, like changing the default folder or choose a custom one each time.
I can totally see users adopt something like /images, /videos etc instead of /assets if it was made easy from Logseq UI.