Sharing links to files that may be updated is an important functionality. There are several discussions on the subject (at least this one and this one). Unfortunately, the problem persists (and these discussions appear closed).
Simple example. I create file a file public/report.pdf and share a dropbox link to it. In another folder, I continue working the "report" (e.g. private/report.pdf). When my private version reaches a new stable point when I am ready to update my readers, I go to the terminal and
% cp private/report.pdf public/report.pdf
Unfortunately, this breaks the link although any normal user would expect it not to. Of course, I could go online and upload private/report.pdf in the public/ folder and the link would be preserved, but that's just painful.
My www.dropbox.com/events page shows that the file was deleted and added. Now you may blame the OS, but the truth is, dropbox should strive to work with the quirks of a not-so marginal OS like, say, macOS. It seems like an easy fix would be to preserve a cache of (path-to-file, link) mappings and, if a new file with the exact same path and name is created before a given mapping is cleared from the cache, assign it the existing link from the cache.
That would solve it for at least me and the people in the discussions above. And frankly, I don't think you could find a user that'd be negatively surprised that deleting a file and recreating one with the exact same path and name did not break a shared link.