It’s not feasible for all broken links to be fixed, but if you reply to the topics with the broken links you’re interested in and the author is still around, they are usually happy to fix those when they get a chance. Most wont bother checking all their links to make sure they still work.
Dropbox broke all their links about a year ago so that’s the main cause of broken links. The original authors would need to re share the file with a new link.